Coolant stop leak products? (TOP 5 Tips)

  • Bar’s Leaks Liquid Aluminum Stop Leak.
  • BlueDevil Hydraulic Stop Leak.
  • AlumAseal Radiator Stop Leak Powder Blister Card.
  • Bar’s Leaks HDC Radiator Stop Leak Tablet.
  • Prestone Complete Care and Stop Leak.
  • ATP AT-205 Re-Seal Stops Leaks.
  • K-Seal ST5501 Permanent Coolant Leak Repair.
  • J-B Weld Radiator Stop Leak.

Do coolant stop leak products work?

Stop leak additives may seal the pinhole leak in your radiator, but they may not deal with the source of the damage. If there are multiple leaks, or if there’s a leak in an area that radiator stop leak can’t seal, it’s time for a replacement radiator.

Can I put stop leak in my coolant reservoir?

Can Bar’s Leaks® Radiator Stop Leak be installed in existing antifreeze coolant? Yes, Bar’s Leaks works with all types and colors of antifreeze coolant and/or water.

Will black pepper stop a radiator leak?

One of them is the use of black pepper to seal small radiator leaks. When black pepper is introduced into the system, the small particles travel to the leak where they expand and seal the leak. The pepper does not deteriorate and will seal the leak until you can get it fixed by a professional.

Does Barr Stop leak work?

Simply stated, it stops leaks in the leak and not on top of the leak. Many radiator stop leak products are made of large particles that clog both leaks and cooling systems! Manufacturers recommend any insoluble particles in the cooling system be no larger than 700 microns.

Can You Use Flex Seal to stop a coolant leak?

Can I use Flex Seal to stop a leak? It’s not true. Flex Seal isn’t made to handle the pressure of a coolant system.

What is K sealer?

K-Seal, K-Seal HD and K-Seal Ultimate are a one-step permanent multi-purpose system for coolant leak repair with over 6 million bottles being sold worldwide to date. It permanently repairs leaks in the head gasket, block, radiator, heater core, freeze plug and water pump casing.

How long does K-Seal take to work?

It’ll take 5 minutes for your engine to reach operating temperature. After that 5 minute mark, run your heat with the A/C on full go for 10 minutes (if it’s getting too hot in there, you can always step outside.

Does putting an egg in your radiator work?

If you are far from a garage and your radiator is leaking, you can use eggs to patch small holes and temporarily plug the leaks. Heat from the radiator will cook the egg whites, and pressure will force the eggs into the holes, fixing the leaks long enough to take your car to a garage for repairs.

Can I put K seal in coolant reservoir?

Yes. K‑Seal is compatible with DEX-COOL and all other types and brands of antifreeze/coolant. Unlike many other products, there is need to drain or flush the cooling system before adding K‑Seal. Just shake, pour and go!

Can you put Blue Devil in coolant reservoir?

Your coolant reservoir is also the first place you’ll be able to notice a leak. If you notice you have a slow head gasket leak, you can use BlueDevil Pour-N-Go to seal the leak and solve your cooling system problems quickly and easily.

Will mustard stop a radiator leak?

Step 2: Add mustard or pepper Try adding 2 tablespoons of mustard powder or ground black pepper to your engine coolant if you have a small radiator leak. The mustard or pepper will migrate to the leak and form a temporary seal. Otherwise, you will probably be better off replacing the radiator. Enjoy a stress-free ride.

Can you fix a radiator leak with JB Weld?

RadiatorWeld™ is a plastic tank and radiator repair kit designed for permanent or temporary repairs on both metal and plastic radiators and plastic liquid storage containers from leaks caused by cracks of 4″ or less and holes up to 1/4″ diameter.

Can I drive my car with a radiator leak?

Driving with a radiator leak is a dangerous operation, as it will very likely cause your engine to overheat. If you are driving down the road and notice your engine is overheating, pull over immediately and let the vehicle cool down.

Best Radiator Stop Leak

Antifreeze/coolant leaks are stopped and sealed with this product. Specifically formulated to eliminate small to moderate cooling system leaks and drips produced by normal cooling system wear and age, Bar’s Leaks Radiator Stop Leak Concentrate is a must-have for every car enthusiast. It is compatible with all brands and colors of antifreeze, coolant, and/or drinking water. As a result, we make the following pledge to our customers: no matter what product you pick, whether it’s our radiator stop leak or something completely different, you can bet on its efficacy and convenience of use.


NOTE: Before using a cooling system that is unclean or partially blocked, it is recommended that it be flushed. Shake vigorously. Stop Leak should be poured into a cold radiator. If there is no direct access to the radiator, the radiator might be installed in the overflow / reservoir tank. One bottle can cure up to four gallons of water. For four-cylinder engines, use half of the bottle. Replacing the cover on the radiator and overflow tank after filling them to the right amount For 15 to 30 minutes, drive or idle the engine.

After a successful installation, leave the Bar’s Leaks in the cooling system to ensure that the system continues to be protected.

  • There is no requirement for specific automotive knowledge.
  • Each of our options is reasonably priced, and will cost you only a fraction of what you would pay on labor with a technician.
  • In addition to our radiator stop leak concentration, we also offer a variety of other chemical repair treatments at Bar’s Leaks.
  • It is compatible with all brands and colors of antifreeze, coolant, and/or drinking water.
  • These films have been produced to make a product that is already simple to use even easier to comprehend and apply to your car.


When it comes to chemical remedies, we at Bar’s Leaks go beyond merely radiator leak sealant. We also provide chemical repair solutions for a wide range of problems, including those involving cooling systems, head gaskets, engine oil, power steering, gearboxes, and other components. As with our radiator sealer, there is no need for any additional automotive knowledge or experience. Each device is reasonably priced and effective, and each works rapidly — especially when contrasted to the cost of seeing a technician on a regular basis.

Many of them, in fact, can exacerbate your current predicament.

In the quest of excellence, these specialists are continually refining our present goods, and they are also constantly inventing new items in response to vehicle manufacturer breakthroughs and new technology.

We’ve been providing customized solutions to ordinary drivers for decades, and our services are significantly more convenient and cost-effective than obtaining expert assistance at a repair shop.

When you’re looking for a radiator leak sealant you can rely on, go no further than Bar’s Leaks. Get your radiator sealer as soon as possible.

20 reviews on average, with an average rating of 4. Lamont’s blog on August 10, 2020 Bar’s Leaks radiator stop-leak concentrate is a concentrated solution for repairing radiator leaks. My vehicle is a 2003 Volkswagen Beetle Turbo ‘S.’ It has a steel coolant pipe with a pinhole leak that has grown over time. It was gushing out so profusely that it was causing my car to overheat. As a result, the automobile decided to shut down without warning. With an eleven-ounce bottle of the ‘Stop-Leak’ in the expansion tank and a few minutes of driving the car at idle (with the heater turned up to full blast), the pinhole was totally sealed up and the coolant line stopped leaking altogether.

  1. It’s impossible to estimate how much money this would have cost me in repairs and towing.
  2. It just costs less than $3.50 to put an end to a major headache.
  3. on January 3, 2020 The heater core has a leak.
  4. As a service manager for an agricultural dealership, I remind my clients that they should never use any chemicals.
  5. The leak was corrected!
  6. However, I discovered that Bar’s Leak is an excellent product, leaving virtually no residue of any kind, and that I could have left the original heater core in place.
  7. Thank you for creating a product that is so effective.


An air leak had developed in the tiny coolant tower that was intrinsic to the non-metallic intake manifold.

Due to the fact that I was too late to be reimbursed for this $800 repair, I put half of the 10 oz.

The leak was stopped in its tracks.


– Dayton, Ohio, USA, July 12, 2019 I’d heard of your goods previously, but hadn’t had the opportunity to put them to use until a few days ago, while participating in the 2010 Hot Rod Power Tour.

I realized I would have to repair the radiator, which would cost around $500, before I could return home.

With only one drop of coolant spilled while driving the automobile from southern Illinois to just north of Minneapolis, I was pleased with my accomplishment.

No matter if you don’t intend to use it, there may be someone else who does.


Well, I had a leak that wasn’t very large, but it was really unpleasant.

Then I went to my local car parts store, AUTO ZONE, and explained my situation to the employee, who then directed me to your product.

I followed the instructions to the letter, and I can honestly say that I have never been pleased with a product; it performed exactly what it claimed to do, and WOW, truly WOW.

I was using 3 gallons of antifreeze every month before I discovered your product, and now I’m back to normal.



The coolant level has remained consistent since I put a bottle of your radiator leak stop in the car and drove it for a couple of days after doing so.


– LoudonPosted on July 12, 2019 Your goods has been much appreciated by me.

We pulled over and let the car sit for a bit before heading to the local gas station, where we discovered that the radiator had broken.

My V-8 allows me to utilize both of them, so I purchased both of them and poured them both into the V-8 before taking off.

Thank you very much, Bar’s Leaks!


When I dumped the bottle into the car yesterday night and drove for approximately 30 minutes in the manner the directions indicated, my radiator was completely full of water this morning.

However, after searching your website and reading the FAQ, I was assured that your product would pass through the number 24 screen that the big three automobiles use, so I decided to give it a try and was very pleased; I purchased another bottle just in case I needed to add more, but I didn’t need to.

  1. W.W.
  2. Every week, I would add coolant to my 2002 Chevrolet Silverado since it had a very little leak.
  3. As a result of reading about your product on another website, I decided to give it a shot.
  4. One week later, my coolant level has remained precisely where it was when I first filled it.
  5. Miguel – San Diego, California – July 12, 2019 After having a cracked cylinder head and thinking it was hopeless for a second, I paid close attention to the directions, and after putting more antifreeze in the radiator, the leak has been stopped ever since.

I have 186,000 miles on my 2001 Jeep Grand Cherokee Laredo and will update this review if anything changes in the future with the vehicle. Thank you for your assistance, amigos! I was able to save between 1000 and 1500 dollars on components and labor.

FAQ(click or touch to expand)

It’s no surprise that our top option for the best radiator stop leaks, ATP AT-205 Re-Seal, has been dubbed “the beast sealant” since it is capable of dealing with both synthetic and traditional oil engines while also enhancing performance. It is also designed to prevent any possible engine obstructions that may occur with appropriate use. There are many different types of radiators and hence a range of stop leak items to choose from among our best selections. These include pills and liquids meant to be used with antifreeze, as well as other products.

Top 5 Best Radiator Stop Leaks

Award: BEST SELECTION WHY WE LIKE IT: ATP’s stop leak may be used for a variety of applications and will not harm your system! It also works with a variety of different oils, making application simple. Pros

  • Rubber is restored, and leaks are stopped. There will be no petroleum distillates. Treatment capacity of up to 6 quarts
  • It is not recommended for use with antifreeze
  • One bottle may not be sufficient.

We have discovered that ATP’s Re-Seal is the finest oil stop leak we have come across. It is the ideal solution for automobile owners who want a single application to assist restore the functionality of their radiator. In addition to traditional and synthetic oils, it is meant to function with gear oils, hydraulic oils, and power steering fluids, among other things. As a result, it is significantly more adaptable than other stop leaks, being able to handle systems more than simply the radiator itself.

It can also assist in extending the life of rubber seals and gaskets!

When working on your automobile, a good car dolly will come in helpful for transporting the vehicle to the location where you need it.

2K-Seal PourGo Leak Repair

Awarded for the sale: HONORABLE MENTION REASONS WHY WE LIKE IT: It’s quite simple to use and is compatible with all forms of antifreeze, and it has the capacity to help seal leaks in a variety of various sorts of radiator systems. With this approach, you may accomplish the project in minutes and be on your way in no time! Pros

  • Antifreeze-ready to the max
  • Seals leaks up to a fraction of an inch
  • Pour and go formula

Unless you have an oil-based radiator, you will need a stop leak that works with antifreeze – and this K-Seal is the finest solution available on the market for these types of radiators. There is no need to drain or cleanse the system; simply pour the solution into the radiator or overflow tank and start your engine. When cured, the recipe is compatible with all types of antifreeze and may seal leaks as small as 1/32 of an inch in diameter. In addition, the formula is excellent for radiators, freeze plugs, heater cores, and water pump casing, and it is the best plastic radiator stop leak.a beneficial characteristic if you aren’t sure where leaks are originating.

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The K-Seal ST5501 Pour and Go Leak Repair is a best-seller in the United States and has sold more than 8 million bottles worldwide; thus, the next time you have a leak in your radiator, make sure to check out this popular sealer.

When working on your vehicle, the greatest car jack may be of great assistance.

3ACDelco Cooling System Seal Tabs Radiator Stop Leak

AWARD FOR THE BEST TABLET REASONS WHY WE LIKE IT: These pills are extremely convenient to store and use whenever you need them, making them an excellent preparedness purchase if you plan to cope with future issues. They’re also non-toxic and may be utilized with all sorts of automobiles, especially antifreeze systems, without causing any harm. Pros

  • The simplest to operate
  • After adding, you’ll be able to drive normally. Over time, they will disintegrate.
  • It takes some time to get things done
  • After usage, a radiator flush is required. Not intended for use with oil-based systems

Another potential leak-stopping option is available in tablet form. In situations requiring long-term storage, such as auto supply kits for a fleet of vehicles, tablets are an excellent choice. Their usage in a wide range of engines (even smaller ones with coolant radiators) is intended to be simple, and they may be administered rapidly by crushing the tablet and putting it to the coolant tank. Also compatible with all DEX-COOL antifreeze varieties, including the “orange” antifreeze that is necessary for metal radiators, the tablets are also available.

Due to the fact that you are already working on the radiator, it may be a good time to consider upgrading to the finest auto brakes.

4Bar’s Leaks 1040 6-Pack

BEST BUDGET HONOURABLE MENTION REASONS WHY WE LIKE IT: There are six high-quality stop leaks in this package at a reasonable price that are intended for long-term use. It is also compatible with all types of oil, as well as gasoline and diesel engines. Pros

  • Excellent sealant for the rear main seal
  • Design of the bottle that is simple to pour
  • Oil spills come in various shapes and sizes, and this product is versatile.

For professional uses or several treatments, you may require a higher quantity of stop leak. This Bar’s leak 6-pack is an excellent purchase because it is quite inexpensive and has an easy-pour bottle style. Designed specifically for rear mains, the formula also works with time covers, cam seals, and other leaks in oil-based systems, although it is not limited to these. Approximately four to six quarts of oil can be treated with a single bottle. Pour it in and hit the road – but allow it some time to do its job.

Because of these long-term characteristics, it may be the most effective stop leak for semi vehicles.

If you have any questions, please contact us.

It could be a good idea to put in the finest auto battery at this time as well.

5Bar’s Leaks Liquid Aluminum Stop Leak

BEST QUALITY WAS AWARDED IN THE SALE REASONS WHY WE LIKE IT: This leak stopper works with all types of antifreeze systems and may be reapplied if necessary to cope with more major leaks.

It is also available in a variety of colors. It is the stop leak that you require if you want the greatest outcomes possible from your cooling system. Pros

  • Extra protection provided by a two-part solution
  • Works in under 20 minutes
  • Treats several components of the cooling system

This stop leak employs a mix of two separate formulae to help seal leaks first, then condition the system to help prevent future heater core leaks and coolant leaks. It comes in a bigger 16.9-ounce bottle for the largest systems. It is compatible with any and all types and colors of antifreeze, including silicate and non-silicate based formulations, without exception. Related: If you’re planning a camping trip, you might want to look into the finest RV toilet. Additionally, the formula aids in the sealing of freeze plug leaks, the reduction of water temperature, and the overall creation of safer conditions for your radiator.

How We Decided

One of the most important characteristics we looked for in stop leaks was how compatible they were with the ordinary engine – and how simple it was to apply them rapidly if a leak was discovered. We concentrated on items that were intended to function with a wide range of antifreeze or motor oils, depending on the type of radiator in issue (we chose products for both categories). Stop leaks that are designed to function with a variety of different liquids are also more likely to be pour-and-go products, which the ordinary customer need when purchasing a sealant of this nature.

That involves assisting in the sealing of fading rubber and plastic gaskets or hoses so that new leaks are less likely to emerge while you hunt for a more permanent solution to your leak problem.

We also gave higher marks to halt leaks that come in easy-pour bottles or that allow you to purchase large quantities in a short period of time for professional purposes.

Best Radiator Stop Leaks Buying Guide

  1. Utilization Ease Don’t be concerned about understanding how to use radiator stop leak formulae – choose one that is simple to use! We like the liquid stop leaks that are available now since they are meant to be measured quickly and placed directly into the coolant tank. When you have a problem, those that don’t need any careful mixing, emptying, or flushing are especially straightforward to apply to the situation. Remember that the container’s design has a role in this as well. For example, When compared to a half-gallon container, narrow containers meant for single use are just easier to pour and measure into. Compatibility What is it that your stop leak is intended to perform, in particular? The objective of stop leaks might differ slightly depending on the manufacturer. Some are intended for specialized applications such as rear main leaks, while others are intended for a broader range of applications. Also, check to see if your stop leak is intended for use with coolant or oil, and that it is compatible with the type of radiator that you have. Safety If at all possible, avoid models that include petroleum distillates since these stop leaks are more prone to cause jams and other difficulties, especially in more sensitive contemporary engines. Look for items that are rated for use with a variety of oils or antifreezes so that you don’t have to mix and match different products. Don’t settle with substandard stop leaks! Your engine’s health might be jeopardized if you don’t use a high-quality product like one of our top selections. Advantages that are not listed above Good stop leaks may also aid in the restoration of outdated rubber seals and gaskets throughout your engine’s internal combustion engine. There is a greater chance that further leaks may emerge if this occurs in the future, and it indicates that the brand is confident in the capabilities of their product.

Radiator Stop Leaks FAQs

These sealants are chemicals that are intended to adhere to the inside surfaces of your radiator. Examples of such compounds include: It is believed that they react with tiny quantities of oxygen present around breaches and form connections with the surrounding metal, thereby mending the leak from within. So, obviously, these products are effective; the major question is how long they will continue to be effective. The majority of stop leak solutions make the claim that they would provide “permanent” seals that will restore your radiator to its original condition.

It’s not a good idea to continually adding stop leaks since they might cause your engine to overheat if you use them too frequently.

Can a stop leak clog cooling systems?

No. Early stop leak products contained plant stuff, which increased the likelihood of your radiator being clogged. Modern versions are a smoother liquid that is less likely to do any damage to your system than previous ones. Always read and carefully follow the directions for the stop leak product you are using, including any instructions on how much to use, what temperatures to use it at, and how to handle your engine after using it, before proceeding. Conditions that are not optimal might potentially cause problems.

Will a radiator stop leak harm my engine in any other way?

They shouldn’t be doing that. Quality stop leaks are engineered to be safe for all engine components, including the pistons and rings. Low-quality versions, when used improperly, are more likely to cause harm to your engine, so it’s critical to get a high-quality product and carefully follow the manufacturer’s recommendations. The type of engine may also be important; certain engine designs are just not as effective at stopping leaks as others; in this situation, seeking an expert opinion may be beneficial to understand more.

Can You Put Radiator Stop Leak Straight into the Reservoir?

This is mainly determined by the sort of stop leak being used. Most consumer-facing stop leak solutions these days are designed to be poured or placed directly into the coolant tank, rather than into the reservoir. Certain are intended to be combined with your engine oil instead, due to the fact that some radiators utilise oil instead of coolant in their operation.

How Fast Does a Radiator Stop Leak Work?

Another section where it’s critical to pay attention to the instructions is this one. Some stop leaks are meant to begin working instantly or within a short period of time. Others are intended to function more slowly, in order to aid in the restoration of older radiators over the course of around 100 kilometers. The amount of damage your radiator has already sustained is another consideration. Stop leaks are intended to assist in the repair of wear and tear, as well as the repair of pinhole leaks caused by that wear and tear.

How do you get rid of the stop leak in a cooling system?

In a cooling system, some stop leaks (for example, tablet versions) should not be cycled for an extended period of time. Other versions may contain substances that, if left in the system for an extended period of time, might block it. The only method to completely eliminate halt leaks such as this is to completely wash out the cooling system. If you don’t have the necessary tools or skills, a local car technician can simply do the task for you.

Do stop leak products really work?

Do stop-leak products actually function as advertised? In order to receive the correct response, it is necessary to be more detailed and to include a few additional words in the inquiry. Consider the example of limiting it down to the discovery of a pool of antifreeze under one’s automobile and the subsequent steps to take. First and foremost, are you certain that you require a radiator or engine block leak stopper product? There are a variety of various reasons why there is a pool of antifreeze under a car, so you’ll need to figure out where the antifreeze is coming from.

  1. The good news for owners of older vehicles is that the older your vehicle is, the easier it will be to track out the source of the problem.
  2. Make a visual look beneath the hood.
  3. Is the air dry?
  4. What do you think about the radiator?

Perhaps the vertical rods with cooling fins are dripping with antifreeze. According to the state of the radiator, if it is leaking antifreeze to the point of a little drop, there is a strong probability that a cooling system stop leak would cure the problem.

Why Use a Stop Leak Product?

The fact that this Rambler American two-door station wagon has a radiator leak does not imply that it is defective; nonetheless, any automobile, even a recently built show car where money was not a consideration, might develop a leak. When it comes to tearing down a show car’s cooling system, it is probable that scratches will be sustained throughout the process of taking it apart and putting it back together. Pouring in a dependable radiator stop leak product is worth a shot at avoiding the need to dismantle the automobile.

Bar’s Leak Heavy Duty Radiator Stop Leak Works Great

Bar’s Leak was developed in California in 1947 and introduced to the aftermarket in 1950. It contains patented Rhizex pellets in a foundation of soluble oil and was first introduced in 1947. I used Bar’s Leak in a 1947 Chevrolet panel truck that had a leaking head gasket that was polluting the motor oil fifty years ago today. The water in the oil of the 216-inch 6-cylinder Chevy Stovebolt engine was a problem. I had sold the truck, and the day before the buyer was scheduled to pick it up, I discovered that the engine oil had become a milky yellow tint.

Alumaseal Radiator Stop Leak Works Great As Well

Alumaseal is a sealant that costs between $2 and $3.50 per tube and is quite effective. I’ve used Alumaseal powdered aluminum radiator stop leak on a number of occasions and have had positive results. In my 1965 Ford F-250 truck, I initially used it to plug a leak in the 352-inch Ford big-block FE engine, which had developed in the engine compartment. I discovered coolant leaking from a 3-inch hairline fracture in the block near the freeze plugs and sprayed Alumaseal into the radiator while it was still working at operating temperature to stop the leak.

I had that 1965 Ford F-250 for another 23 years and it never had a leak in the engine block again.

How to Find A Cooling System Leak and Stop It

The first step in locating a cooling system leak is to thoroughly clean the engine compartment before starting the engine and attempting to locate the source of the antifreeze leak. Although the engine compartment appears to be in disarray, the engine is clean enough to detect an exterior leak. The first step in identifying an internal leak is to do an engine oil inspection. If the engine oil seems to be milky, check for a blown head gasket, cracked cylinder head, or cracked cylinder head block.

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Can a Modern Radiator Stop Leak Work in an Old Car?

Modern radiator stop leak products can be used in the cooling system of an older vehicle. Cars as ancient as this Model T Ford did not have a high-pressure cooling system and ran at temperatures that were normally below 160 degrees Fahrenheit, according to the manufacturer.

Instead of antifreeze, water was used as a coolant, with soluble oil added to lubricate the water pump and prevent it from freezing up. The same principles will apply to stop leak products. K-Seal ST5501 Multi Purpose One Step Permanent Coolant Leak Repair, Blue : Automotive

This was reviewed on May 15, 2016 in the United States. First and foremost, allow me to provide you with some background information. Even though I work for AutoZone, I perform my job honestly and do not try to persuade people to buy things in which I have no interest. We just had a sale of some dreck that I wouldn’t sell to my least enemy, thus I didn’t sell it to anybody else either. When I refuse to comply with a customer’s insistence that, for example, 20W50 would function perfectly in a 0W20 application, I am called upon to do so.

  • After consulting with a number of technicians, it was determined that the best (and really only) course of action was to replace the radiator.
  • And that’s exactly what I did, despite the fact that my perfectly functional themometer never went into the red without coolant, no matter how hard I drove or for how long I was on the road.
  • As is the fact that my previous engine ran for 45 miles without oil and with a bent or thrown rod, among other things.
  • Prior to the installation, though, I had a notion to myself: “I receive a 20 percent discount on anything I purchase.
  • The nicest part is, of course, that I no longer require the radiator.
  • It is available at a very low cost.
  • 2.

This was critical to me because I had no clue where the leak was coming from.

A literal “Pour-N-Go” convenience store.

Leaving it throughout the balance of the coolant’s useful life is quite OK.


Normally, I would argue that bigger is better, but in the case of additives, where overfilling may be a dangerous/hazardous issue, having something that performs its function while taking up a minimal amount of space is quite important.however, I was highly skeptical that it would work.

During my AutoZone training, I learned that if your coolant was leaking out completely in less than 2 weeks, then stopping the leak was more than likely a waste of money.

I had recently changed my radiator cap, which had prevented it from seeping out within half a day and causing steam to emanate from under the hood, which would have been disastrous.

I truly did this in the parking lot of AutoZone on my day off, in front of my store manager and other colleagues who were on hand to see it.


After driving, it’s a good idea to wait at least 30 minutes for this to occur.

I do recommend that you let your coolant run fully empty (or at the very least down to the “LOW/FILL” line) before starting your engine.

Simply get the cheapest appropriate 50/50 coolant that you can find for your car; they are all essentially the same, with the only variation between manufacturers being packaging (and perhaps Peak’s “Lifetime Radiator Guarantee” if you have one).

If your coolant is entirely depleted and you drive a General Motors car, there is no danger in replacing it with the yellow coolant rather than the pink/red Dex-Cool product.

Also, have it pre-mixed if possible.

Do not take the possibility of mixing it yourself, especially if you do not have to.

I firmly shook the container of K-Seal for a little more than 30 seconds before using it.

So shake it up like a Polaroid photograph!

Fixing your radiator may be made more enjoyable by dancing while doing it.

After re-inserting my funnel into the coolant reservoir, I simply poured the K-Seal into the reservoir.

According to the bottle, you may either go directly through the radiator cap or utilize the overflow reservoir, with the overflow reservoir taking a bit longer than the radiator cap.

This is the only option I would recommend unless you just do not have access to a reservoir tank in the first place.

Oil changes that take 5-10 minutes are a fraud – it takes at least 20-25 minutes to properly (and fully) change an oil and filter.

Take the additional time now to avoid having to take even more time later.


It will take around 5 minutes for your engine to reach operating temperature.

I was doing it for basically the whole duration of this anyhow), then turned it off for the final five minutes.

Although mine did not appear to be leaking, it is definitely a good idea to do so regardless of whether your floors are soaked in coolant or not.

Of course, you’ll want to make sure you have enough petrol in your tank for this as well.


Get out on the open road and onto the interstate.



It’s possible that the leak continues for a short period of time, but ideally not past the low line.


Make sure it doesn’t budge from its position.

If it’s still leaking, keep an eye on it continually until/if it reaches the Low line, top it off, and keep monitoring.

9) If everything is well now, return the +$130 radiator and use it towards a vacation or weekend trip that you can now afford to go a great distance for!

So, to summarize, this product was absolutely effective for me, despite the fact that I did not anticipate it to be so.

I achieved good results, and I expect to continue in this vein.

I have not seen anything becoming blocked, which is a typical problem with these sorts of goods, but I might be wrong.

Please make sure to click on the “Helpful” icon if you found this review to be of assistance.

I was dubious, but I needed to know.

In my case, I had a 2002 Land Rover Discovery II SE, and I’d previously spent $350 trying to figure out what the problem was, with no luck.


I viewed a number of YouTube tutorials and came across one that suggested the following: One does not have to pour the entire bottle of wine.

I had a leak that was active and seeped beneath the driver’s side window every 5 seconds!

A clean plastic 2 liter soda bottle was used, into which I put about a third of the K-Seal and then filled it the rest of the way with coolant.

I just let it idle and kept it going.

After approximately 5 minutes, there was a slower leak and the coolant level in the reservoir was low – so I repeated the procedure with an extra third of the coolant mixed in.


Backing the Land Rover down my lengthy driveway on an inclination such that the hood was higher than the rear bumper was a challenge for me (so coolant could properly fill the system,).

As a result, it was almost completely vacant.

As soon as I pulled my foot off the brake at a green light, there was a stronger reaction to the gas pedal, and it wasn’t stuttering any longer – it was virtually chewing at the bit to move forward.

Back at home, a new piece of cardboard was used to store it overnight.

Still apprehensive, I put it through its paces in my area and found it to be flawless.

As a result, I ended up using around two-thirds of the bottle and will have the rest on hand in case there is another leak.

Combines with all antifreeze products.

The radiator, head gasket, freeze plug, cylinder heads, heater core, water pump casing, and engine blocks are all repaired as a result of this procedure.

Purchase that has been verified I was really skeptical, and I was a little concerned that this might do more harm to my 2003 Honda civic.

When I got to that point, I just poured it in and let the car run for approximately an hour while keeping an eye on the temperature monitor.

So I took it for a 15-20 minute vigorous drive, during which it performed admirably, generated heat, and maintained an engine temperature below half.

That has likewise come to an end.

It helped me save more than $1000.00!

Purchased in the United States on August 17, 2016 and reviewed on August 17, 2016Verified Purchase I was apprehensive about how and whether this thing would work.

Several months had passed since my undercarriage totally froze when I was driving home in a spring blizzard, and the coolant was slowly seeping.

I applied the k-seal this morning, drove home with the air conditioning running, and then parked the car in my driveway.

There was no leak after I let the car sit for around 30 minutes. Normally, I’d have roughly a water bottle’s worth of water remaining, so I’m completely taken aback. I’ll update the post if anything changes, but thus far everything has been positive.

Top reviews from other countries

5.0 stars out of 5 for this product However, it is useful for a quick repair on a cheap motor. On November 8, 2017, a review was published in the United Kingdom. Purchase that has been verified The presence of coolant mixing with oil/creamy fluid on the interior of the oil cap is a very early symptom of head gasket rupture. Applied this little container of K-Seal to the engine and saw no overheating, no running troubles, no loss of oil or coolant, and no mixing seemed to have occurred. Not for a high-end vehicle (I just put it in my £300 runaround to give it a few more months, if not years), but it’s excellent for a quick fix on a cheap motor that would otherwise be discarded.

  • On October 29, 2019, a review was conducted in the United Kingdom.
  • Numerous horror stories regarding this product that can be found online are, quite honestly, the result of the user’s absolute incompetence and idiocy, as can be shown in the examples below.
  • You really must determine the volume of water that your engine consumes before using ONLY the suggested amount of the product to match!
  • In the case of a conventional MEDIUM engined UK car, dumping the entire contents into the cooling system is a recipe for disaster!
  • Here’s how it works in my particular case.
  • When the machine was left standing for a few days, it would misfire and pause for around 10-20 seconds before working normally again.
  • When you start the automobile, the plug is drenched with water, therefore it will not be able to ignite, resulting in a misfire.

A low water level in the radiator and header tank, as well as the use of an inspection camera down the plug hole, revealed that there was coolant present in the radiator.


Coolant levels in the header tank are no longer dropping, and costly repairs have been put off until a later date (if at all).

5.0 stars out of 5 for this product One of the very few fast fixes that truly works is this one.

Purchase that has been verified Simply said, it is as simple to use as topping up your radiator, so there is no need for rocket science here.

Take note that this type of gear is typically referred to as “get me home” equipment, but as a qualified DIY mechanic, I believe that it does exactly what it says on the tin and is suitable for use as a permanent installation.

5.0 stars out of 5 for this product Applied to the Daihatsu Hijet to alleviate overheating.

This was applied to a Daihatsu Hijet that was experiencing an unusual overheating problem.

I was suspicious that the gasket had failed, but I didn’t want to fix it because it would have cost more than £300.

Still early in the game, but as long as it lasts a year, I’ll be content.

On November 29, 2020, a reviewer in the United Kingdom expressed satisfaction with their purchase.

I had been filling my expansion tank with water every three to four days for more than a week before using K-Seal, so I was looking forward to seeing how it worked. My water level has remained constant, thus I am quite pleased and satisfied with this device, which I would absolutely suggest.

The Best Radiator Stop Leak: A Complete Buyers Guide

You’ve noticed a puddle of liquid below your automobile, and you’ve determined that it is the result of a radiator leak. It’s time to take your wallet out of your pocket and watch the cash fly away. If you don’t want to spend a lot of money on expensive labor charges owing to the complicated repair required to access to the radiator, you might consider using a radiator stop leak to solve your problem. Using this method is a quick and simple cure, and you can generally add it immediately to your cooling system, resulting in a repair that is noticeable within minutes of implementing it.

What is it about stop leak formulae that causes so many mechanics to advise against using them?

In this post, we’ll assist you in understanding how to maintain your car and shop for the best radiator stop leak, including how to choose the finest one and which ones we recommend.

Up Front Best Radiator Stop Leak

  1. Overall, the best product is Bar’s Leaks Liquid Aluminum Stop Leak. Repair Stop Leak Re-Seal Tool (ATP AT-205 Re-Seal Stop Leak): Multipurpose Tool It is highly recommended to use the K-Seal ST5501 One-Step Permanent Coolant Leak Repair Kit. Bar’s Leaks HDC Radiator Stop Leak Tablets: The Most Reliable on the Market
  2. Bar’s Leaks 1109 Block Seal Liquid Copper Intake Fluid: a one-step sealer for copper inlets and drains. Prestone Radiator Sealer Stop Leak: Superior Sealing Performance at a Low Cost

Keep These Factors in Mind

When most individuals think of fixing their automobile themselves, they envision a time-consuming operation that necessitates extensive technical expertise. However, this is not always the case. Simply putting the liquid into the appropriate tank and allowing it to do its work is all that is required for this job. The difficult aspect is determining which leak product is the best to purchase. When it comes to choosing a radiator stop leak solution, there are a few important considerations to bear in mind first.

  • Do you have a strong mechanical background? – While pouring stop leak formula into a tank does not need much understanding, it is important to ensure that the formula is placed in the proper container. Make sure you understand what you’re doing or seek assistance from someone who does
  • If you stream this into the incorrect area, it will have a disastrous effect on your automobile. Do you think you need to cleanse the system out? – Many varieties of sealant need you to cleanse the cooling system before pouring the liquid into it, whereas others do not require this and do not require it. Your degree of skill determines which one you should choose and why. If you know how to flush the system, those sorts of sealants will function more successfully
  • But, if you don’t, you’re better off choosing a non-flush leak remedy rather than one that requires flushing. Make certain that you choose the appropriate one depending on your experience
  • How much does it set you back? – Despite the fact that a radiator stop leak solution is far less expensive than having to disassemble the vehicle, there is still a cost connected with this endeavor. Consider your budget and your research to ensure that you don’t end up purchasing a low-quality leak-stopping solution that doesn’t perform as well. Is it functional in your vehicle? – Not every solution is suitable with every type of automobile. Especially if you have an older vehicle, you should verify online or consult the owner’s handbook to be sure that the stop leak formula will not do extra harm to your vehicle. Is there a genuine leak here? – You might not even be aware of where the leak is coming from, which is amusing to consider in this context. You want to be certain that your radiator fluid is in proper working order and that you understand what sort of liquid is leaking from your vehicle. When it comes to leaking, there are several possibilities, so conduct your study or seek the advice of an expert before making your final selection. What is the size of the leak?– It’d be wonderful to assume that pouring a leak remedy down a hole would solve all of your problems, but that isn’t usually how things work out. If the leak is large and occurs quickly, a radiator stop leak will most likely not be sufficient to complete the task. Then you’ll want to get professional advice on what to do next
  • This will be your best option.
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Different Types of Radiator Stop Leak

You should now consider what sort of formula you intend to use if you have determined that a radiator stop leak is required. Because there are several different possibilities, be certain that you choose the one that is most appropriate for you and your vehicle.

  • Liquid– These are the most prevalent type of liquid, and they are available in a variety of forms and sizes. They are normally pre-mixed with everything you need, so you can just pour it in and forget about it
  • But, they may also be made from scratch. Powder– These are also available in a variety of forms and sizes, and all that is required is that you pour it into the car’s radiator. Tabs– Although many mechanics disapprove of them, they are nonetheless widely used in a variety of applications. You may dissolve them directly in the car’s cooling system by dropping them in, or you can dissolve them in warm water first before putting the mixture into the car’s cooling system.

How to Find the Best Radiator Stop Leak

It is not always simple to choose the best stop leak formula by comparing several options. Because there are so many things available, it is difficult for the ordinary consumer to select just one of these products. As a result, research is really important because we are talking about your automobile. You want to be certain that you don’t do any harm to your car, so picking the appropriate decision is critical to this goal. The first thing you should consider is how long you have been experiencing a leak.

If you haven’t addressed the leak for a few weeks, you may need to purchase additional leak formula or get expert assistance.

Here are a few other suggestions to assist you in your search for the finest radiator stop leak:

  • Clogging– You want to avoid clogging at all costs, and the most typical places for it to occur are around the heater core and the fan motor. Consider how well-known and effective the product is in terms of its ability to move through the engine and patch leaks without interfering with the functioning of your engine. Chemicals– Different formulations contain a variety of distinct chemicals and components, each of which will have a different effect on your engine. Among the most difficult to come by materials are liquid aluminum and extreme cold, both of which have a solid reputation and are typically safe to use.

Radiator sealant is a handy and practical product for individuals who want to extend the life of their vehicle without having to spend a lot of money on maintenance.

However, it’s crucial to remember that these are not long-term fixes, and that the leak may indicate the presence of a longer-term problem down the line. If you suspect that your leak is significant, it’s always advisable to get professional advice from a qualified professional.

Top 6 Picks for the Best Radiator Stop Leak

Knowing how to pick the best radiator stop leak, below are some highly suggested examples to make your decision a little bit simpler.

1.Bar’s Leaks Liquid Aluminum Stop Leak

It’s best to take the bottle and walk away as soon as the name bar Leak appears on it. Those listed above are the best products available on the market, and they are well-known for their ability to properly plug coolant leaks. This radiator fluid aids in the sealing of radiator leaks, freeze plug leaks, and head gasket leaks, among other things. Bar’s leaks, liquid aluminum, and Xtreme cool are used to lower the temperature of the surrounding area. By sealing the leak and conditioning the system, these two work in unison to provide the best results.

The primary drawback of stop leak formulations is that they are only temporary; however, this one is said to be permanent, which is a significant advantage.

This product may be added straight to your coolant system, allowing you to stop the leak in less than 20 minutes.


  • There is no need to purge the system
  • This is an advantage. Includes liquid aluminum and Xtreme cool to keep you cool. Definitely recommended
  • It is effective
  • It is quick. It’s a remedy that’s almost permanent


‘This radiator and cooling system stop leak formula serves as a multi-purpose tool for the complete radiator and cooling system.’ Not only is it a top-of-the-line leak-stopper, but it also helps to bring your seals and gaskets back to life with the rejuvenating ingredient it contains. Additionally, ATP does not necessitate the flushing of your system, and it is compatible with both traditional and synthetic oils, as well as power steering fluids. It’s powerful enough to do the task at hand without causing damage to other components of your car’s engine or transmission.


  • Formula with dual action
  • It does not necessitate the flushing of the system. It is compatible with both traditional and synthetic oils.


  • It has problems with gaskets and seals
  • It does not contain liquid aluminum
  • And it has other issues.

3.K-Seal ST5501 One Step Permanent Coolant Leak Repair

This is the formula to utilize if you’re seeking for a highly recommended leak repair formula that is used by roadside help businesses all around the world. A head gasket leak, engine block leaks, radiator leaks, and water pump leaks may all be fixed quickly and permanently with this product. This recipe will work for you no matter what sort of leak you are experiencing. It quickly begins working to locate and fix the leak as soon as it is introduced into your system. It is constructed of microfibers that, when they come into touch with one another, form a mesh seal over the leaks.


  • Exceptional reputation
  • Works promptly
  • Repairs all sorts of leaks


If you’re not a fan of the entire liquid concept and would prefer something a bit more straightforward, you could try this leak tablet from Bar’s Leak instead. These provide excellent value for the money, and they can be stored virtually anyplace. They are responsible for sealing leaks, controlling electrolysis, lubricating, and conditioning your cooling system. In order for them to operate, you must first dissolve them in warm water before proceeding. Once you’ve poured the liquid into your system, they begin to function fairly immediately, usually within 15 minutes of doing so.

This organization has over 70 years of expertise in repairing automobile leaks, therefore it is always beneficial to work with a reputable company.

Amazon These days, we all enjoy using our tablets for a variety of activities such as reading, gaming, and surfing the web.

Your radiator, like so many other components in your car, requires routine maintenance to keep it operating at peak performance.

This is not necessarily the case. Purchase from If you click on this link and make a purchase, we will receive a small commission at no additional cost to you. GMT: 12:04 a.m. on January 7, 2022


  • Strong corporate reputation
  • Tablets rather than liquid
  • Excellent value


Imagine you had a major leak and you don’t have the funds to pay for a costly repair. What would you do? What should you do if you find yourself in this situation? You could either call your local technician and find out the awful news, or you could get this antifreeze stop leak product instead. For bigger leaks, this one is meant, and it works swiftly and at a fraction of the cost of a repair service. Bars Leak has built a solid name over the years, and this leak repair performs an excellent job of assisting them in maintaining that reputation.

The formula cures leaks on contact and prevents further leaks by binding to your system and stepping in as necessary to prevent further leakage.


  • Strong leak-stopping formula
  • Effective on major leaks
  • Excellent corporate reputation
  • Prevents future leaks


Here’s a brand that you’ve most likely heard of in the past. The formula for this leak stopper is trademarked, and it begins to work instantly upon contact with leaks in your radiator, water pump, or heating core. This liquid also has the additional benefit of protecting your automobile from corrosion and pitting. In comparison to some of its competitors, the key distinction between this stop leak device and others is that it not only stops leaks, but it also detects corrosion spots in your system and regions that are beginning to fail.

  • This will assist you in getting rid of any immediate leaks as well as preventing them from occurring in the future.
  • In addition, you won’t have to be concerned about this one clogging up your system.
  • Prestone Radiator Stop Leak.
  • Purchase from
  • GMT: 12:04 a.m.


  • On touch, this product fixes rust
  • It works with many different sorts of leaks
  • And it does not clog your system.


Brand Type Fixes Large Leaks? Requires System Drain? Price
Bar’s Leaks Liquid Aluminum Liquid No No $
ATP Re-Seal Liquid No No $$
K-Seal Liquid No No $$
Bar’s Leaks Tabs Tablets No Yes $
Bar’s Leaks Liquid Copper Liquid Yes No $
Prestone Sealer Stop Leak Liquid No No $

Let’s take a look at each stop leak formula in comparison to one another. If you had to choose just one, and you wanted to go with a product that would work well in a variety of situations and had a good reputation, we would recommend the Bars Leak Liquid Aluminum stop leak solution. This product has received a large number of good reviews, as well as a few negative ones. It works well, and it has survived for such a long time as a result of this. If you’re on the fence about which product to purchase, this is the way to go.

The use of these two items will also provide a long-term solution to your leak, which means you won’t have to return to it in a few months and refill it with more product.

To further persuade you, the final advantage we have with Bar’s Leaks is that you do not need to cleanse your system after putting the product into your system.

Keep a bottle of WD-40 in your car in case you come upon another leak. If you’re putting money down for the future, you don’t have to be concerned about spilling it on the side of the road. Advanced mechanical expertise is not required to complete this task.


Is it safe to use radiator stop leaks? When you use a radiator stop leak in the proper manner, it may effectively stop leaks in your system without causing damage. This, however, is not a permanent solution, and you will ultimately need to add extra radiator stop leak liquid to your system. Is it possible for a radiator stop leak to cause overheating? Some users have reported that they have encountered a blocked radiator as a result of the use of low-quality stop leaks, which clearly increases the danger of overheating.

How long does it take for a radiator to stop leaking?

You’ll need to replenish your radiator at some point, and most individuals say that they replace their radiator stop leak after around 20,000 to 40,000 miles on the road.

Final Thoughts

The selection on a radiator stop leak for your automobile should be straightforward at this stage. There is nothing worse than discovering a puddle of liquid below your car, but having tools like these makes it a lot easier for car owners to deal with the situation. Fortunately, the most of these devices are virtually indestructible, and the vast majority of individuals will never have to worry about a radiator leak again. As previously said, the Bar’s Leaks line of goods is a good choice due of their great record for success and the large range of items available.

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