10 Best Radiator Stop Leak in 2020 – Reviews & Buying Guide

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One of the most worrisome discoveries common with most car owners is seeing a pool of liquid right under your car and here is one thing, a leak can be quite expensive to fix especially if you have a radiator that leaks.

Fortunately for all vehicle owners, there is something called a radiator stop leak sealant which is quite easy to fix and most times do not require any form of preparation but just being added directly to your vehicle’s cooling system.

The best radiator stop leak products are scattered all over the market but how do you identify them?

A Complete Buying Guide On Finding The Best Radiator Stop Leak

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These sealants comprise the mixture of fibers, ceramic particles and also metals which makes it very effective and gets it to work in about a few minutes. Most people still do not know how these sealants work or even what product to settle for but not to worry because our best radiator stop leak review has got every question covered. Here are the best radiator stop leak products;

1. Bar’s Leaks Liquid Aluminum Stop Leak

best radiator stop leak

The Bar’s Leak Liquid Aluminum stop leak is without any doubt or argument the best radiator stop leak product that you can ever come across on the market. It is known to be very effective when it comes to sealing leaks like freeze plug leaks, radiator leaks, heater core leaks as well as gasket leaks. It makes use of Xtreme cool and liquid aluminum in cooling water temperature and I guess by now you would be wondering how the liquid aluminum works.

It is a very powerful ingredient that works in conditioning systems and sealing leakages. What this product is good at is not just for sealing of leakages but also for making sure that the same leakage issue doesn’t occur or come up in the future.

What makes this product outstanding is because it doesn’t require flushing of antifreeze away from any system as it is designed to go directly into your car’s cooling system.

Liquid aluminum has the ability to work with various coolants like blue, red, pink, orange, yellow and even green non silicate and silicate-based HOAT/OAT antifreeze. It only requires just twenty minutes to seal up leaks and it also works great with water.


  1. Doesn’t require the flushing out of antifreeze from your car system
  2. Prevent future leakages
  3. Works with different types of coolant

2. ATP AT-205 Re-Seal Stops Leaks

If you are in search of a fast and safe radiator sealant the ATP AT-205 re-seal sealant is one product you should consider settling for as it features professional-strength required in sealing up leakages. This radiator sealant isn’t just formulated to stop leaks but it can also be relied upon when it comes down to rejuvenating hydraulic systems, power steering systems, transmission systems, engine gaskets and rubber seals. Flushing the entire system before adding this sealant isn’t required as this sealant is manufactured to mix properly with synthetic and conventional oils.

Safety is also another feather to the cap of this product as users are assured that it would not cause damage to any internal component but you can rest assured that this radiator stop leak would repair dry and worn out seals. Users would find this product very easy to make use of and it also boasts of having a special formula that promotes it blending with oil as well as adequate circulation even when the car is in use.

Key Features:

  1. Would not damage vital internal parts of any vehicle
  2. Boosts up dead systems in your vehicle
  3. Mixes with oil and circulates properly throughout the engine

3. K-Seal ST5501 Permanent Coolant Leak Repair

Everyone has various reasons why they feel they need a radiator sealant. You might be dealing with either an engine block leak, head gasket leak, water pump leak or even a radiator leak and whichever the case might be, we want you to know that the K-seal coolant leak repair product is on hands to help tackle such problems.

Adding this K-seal coolant leak repair is very easy to use and all that it needs you to add it directly into the coolant system so as to produce a fast and long-lasting solution.

This product would also ensure that your engine continues to function as normal and it also makes sure all cracks and holes are sealed up permanently. Its special material coating contains high-quality microfibers that comes together to form a seal when it senses a leakage. This seal that it forms is quite permanent and strong and also offers users professional results.

Key Features:

  1. Would seal up every hole and crack permanently
  2. Its microfiber materials come together to create a seal
  3. Would deliver excellent and professional results

4. Bar’s Leaks HDC Radiator Stop Leak Tablet

The only difference in this product from others that we have talked about is that this product isn’t a liquid product as it comes in its tablet form and even at that, it is one of the most effective radiator stop leaks that you can ever settle for as it also offers great value for the money spent in purchasing it.

This product is a good buy as it can prove to be beneficial to your car in so many ways and one way it proves to be beneficial is by helping to control electrolysis and not just stopping leaks.

This product is also ideal for prevention corrosion, preventing rust, helping in conditioning your car’s cooling system and also lubricating water pump seals and this shows that it is beneficial all round for every car. It is also very simple to make use of as all it takes is just for you to add these tablets to warm water.

This radiator stop leak promises to stop coolant leaks, internal and external leaks as well but in some cases, it might require two applications for it to be effective.

Key Features:

  1. Manufactured by a high profile and reputable brand
  2. This product is multi-functional as it works in various aspects of any vehicle
  3. Also useful in controlling electrolysis

5. Interdynamics Certified Engine Cooling Systems UV Dye

This product is also slightly different from all others that we have talked about in the sense that it isn’t just all about fixing leaks but it is also very useful when it comes to discovering if your system has any leaks.

The addition of this product into your cooling system would tell you where there is a leak in your system and if you must know, this product is a professional grade product as it only comes with just one application into your engine cooling system.

A UV blacklight is also required if you must make use of this product in your engine’s cooling system and it can also be used on various types of vehicles except for newer and 1996 GM models. You can also bank on this product to work with various types of antifreeze apart from the DEX-COOL coolant. This product sells for a reasonable price and has earned massive positive reviews.

Key Features:

  1. This is a dye product that is capable of staining the skin on contact
  2. Detects where leaks occur in your engine cooling system
  3. Professional grade product

6. Genuine GM (12378255) Fluid 3634621 Seal Tablet

This is the ACDelco cooling system seal tabs and one of its great features its ability to offer great service for the money spent on it. Most people who have tried out this product came back describing it as a low-cost miracle and even though some other people may think that this is a good radiator stop leak sealant, the truth still remains that it has some good and positive effects that make it good all round.

This product also comprises of an organic and original formulation which makes it specifically for use in radiator systems and this seal tabs are formulated not just for the purpose of sealing leaks but also for preventing leaks from happening. It is designed using a material that is capable of sealing a vehicle’s system cooling porosity and this, in turn, helps in preventing corrosion. It is a non-toxic product and also DEX-COOL compatible.

Key Features:

  1. Very affordable product that seals leaks in your vehicle’s cooling system
  2. Seals leaks and also prevents leaks from occurring
  3. Also helps in preventing corrosion

7. Bar’s Leaks 1109 Intake and Radiator Stop Leak

Up next is another Bar’s Leak product to make it to our top 10 best radiator stop leak review and if you are shopping for a radiator stop leak to seal heater core leaks and larger leaks then this is the right product for you. If you want to fix blown head gaskets, blocks and also freeze plug leaks you can also count on this product to do the trick and does all these at a very affordable price.

This product is a one-step sealer and this is what makes it quite special from all other radiator stop leak products on the market and it also contains a sodium silicate formula that is compatible with antifreeze which is why it is quite necessary for one to drain his or her cooling system before making use of this product.

You can also make use of this product with just water and you can count on this product not just to seal leaks but also to remain in your vehicle’s cooling system to make sure there are no more leak issues.

It also makes sure corrosion doesn’t happen in the future.

Key Features:

  1. Protects against future leaks and not just seals leaks
  2. Requires draining of your cooling system before use
  3. Can be used in various application like fixing blown head gasket and freeze plug leaks

8. BlueDevil Radiator & Block Sealer

If you want a radiator sealant that would seal up all leaks in your cooling system permanently then the BlueDevil Radiator and Block Sealer is the ideal product for you. Every product is manufactured to stand out in its own way and this one stands out from others as it is able to work amazingly well on metal radiators, aluminum and plastics. It is an extremely safe way of sealing leaks permanently and users would also find working with this sealant very simple and easy.

It is made out of a special non-fibrous or solid materials formula which is why it would not clog or harm your vehicle’s cooling system. However, it acts by binding with metal, alloy, aluminum and also cast iron as well as being compatible with diesel and gasoline engines. It also acts by bonding to the weakest points in your vehicle’s cooling system and this is where it creates a permanent seal that would work with the heat in your vehicle to contract and expand.

It can also be added directly to your vehicle’s cooling system.

Key Features:

  1. Doesn’t require draining or flushing or your cooling system but can be added directly
  2. Compatible with diesel and gasoline engines
  3. Manufactured to offer a permanent solution to leaks in your cooling system

9. J-B Weld DS-114 Automotive Accessories

This product features a non-toxic, gentle but yet tough formula that would seal leaks and also make sure rust doesn’t occur in your engine’s cooling system. That isn’t all about this product as it also helps in lubricating the internal components of your vehicle’s cooling system. It is one that claims to offer a lasting solution to leaks that occur in the radiator of your trucks, vans, cars, tractors and bus and it is also very simple to make use of.

It is one of the safest ways of sealing leaks in your vehicle’s cooling system as it would not harm or clog your cooling system in any way and if you also want an affordable way of sealing leaks in your cooling system then this is the right product for you instead of always going to the mechanic.

When dealing with larger leaks, you can catch the fluid and run it constantly until you finally seal the leak but you should check the body of the package if it is compatible with your vehicle before opting to pay for it.

Key Features:

  1. Has a gentle and non-toxic formula
  2. Would not harm or clog your vehicle’s cooling system
  3. The very simple method of application

10. Prestone AS145 Radiator Sealer Stop Leak

If you are searching for a product capable of sealing leaks fast then the Prestone Radiator Sealer Stop Leak is just the best product for you. This is because it has been designed using a patented formula which makes it acts fast when it comes to sealing leaks in your vehicle’s radiator heater cores and also in your water pumps. Just like other products that we have reviewed, the Prestone Radiator Sealer Stop Leak also prevents corrosion and pitting.

Many at times, this product is what customers believe was manufactured to take the sealing game to the next level and its formulation features the combination of synthetic and natural fibers which seals leaks quickly and with ease.

Even if it helps in sealing leaks in your vehicle’s cooling system, you do not have to be worried about it clogging heater tubes or radiator.

Key Features:

  1. Has a fast-acting formula
  2. High-quality product
  3. Also stops corrosion and pitting

Best Radiator Stop Leak Buying Guide

If you are faced with fixing a problem with your vehicle yourself then there is a possibility that the variety of products on the market might overwhelm you but below are factors that we discussed that would make the task much easier for you.

Factors to Consider When Shopping for a Radiator Stop Leak

There are so many components your vehicle possesses to function properly for its engine to run smoothly and one of such components is a radiator. The purpose of a radiator is to cool the engine by making use of a liquid coolant. The reason is that engines tends to break down as a result of overheat which also progresses to a leak in the radiator.

A radiator stop leak is the only way you can fix such an issue but here are certain factors that would be key in helping you select an active and effective radiator stop leak.

  1. Vehicle Compatibility – buying a product that isn’t compatible with your vehicle could be very damaging so it is necessary that you check and confirm first before making any purchase
  2. Budget – these sealants tend to have varying prices so try to have a budget but still yet, never compromise on quality.
  3. Can You Do It Yourself – adding a radiator stop leak to a cooling system isn’t so much of a difficult task but if you don’t know what exhaust is or what a gasket is then it is best for you to seek professional help and not do it yourself
  4. Flushing Out Your Cooling System – some radiator stop leaks might not require flushing but just direct addition into your cooling system while other products might require so it is also necessary that you find out which rule the product you are going for demands before carrying out any action
  5. Size of Leak – if you are dealing with a small-sized leak then a radiator leak is enough to seal it up but when dealing with a large-sized leak you might need to get professional help or make use of twice the amount of the sealant you are making use of

Final Thoughts – Our Number One Product

Selecting the best radiator stop leak can be a very difficult task but the product which we have found to be a very good choice for all kinds of leak and vehicles is the Bar’s Leak Liquid Aluminum Stop Leak.

It is one of the most popular leaks that you can ever come across on the market and you can bank on this sealant to deal with heater core leaks, gasket leaks, freeze plug leaks and also radiator leaks.

The material used in making this stop leak doesn’t just seal leaks but also helps in conditioning your vehicle’s cooling system and it doesn’t require flushing but direct addition into your vehicle’s cooling system. It is also very fast as it takes about twenty minutes to seal leaks, others might require up to five hours.


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