10 Best Radiator Stop Leaks Reviews [Updated 2020]

best radiator stop leaks

Radiators are heat exchangers which collect the heat from the engine and transfer it to the surrounding air. There is a particular chemical used in the engines called coolant, which is stored in a reservoir.

This chemical coolant circulates to almost all parts of the engine to collect the heat. Then brings it to the radiator, which is cooled by the sucked air from the radiator fans. Most frequently, the radiator leaks occur through the rubber along the edges.

Due to the heat, age, wear, and tear, the rubber gaskets get worn out, which results in the leakage of the radiator.

This leakage rectified by using the radiator stop leaks. They are chemical solutions that bind up with seals the leakage.

The dense chemical combination in the radiator also forms a coat over the leaking regions and hinders the leak.

Such chemicals shall be of great use not only to car enthusiasts but also to the owners of old cars. Have a glance at the article below to collect more details about various outstanding radiator stop leaks.

After 46 hours of research, we’ve made the list of the best radiator stop leaks, and it will be helpful for your purchase.

Best Quality


Prestone AS145

Best Overall

atp at 205

ATP AT-205

Best Value

k seal

K-Seal ST5501

Best Radiator Stop Leak- 10 Products Reviewed

1. ATP AT-205 Re-Seal Stop Leaks

ATP AT-205 Re-Seal Stop Leaks is an outstanding product, which is usually available in the form of liquid.

Weight: 2 lbs

Model: AT-205


  • Good inhibitor
  • Merge well
  • Work efficiently

It is mentioned being a perfect formulation to treat leaks because it rejuvenates the seals and its associated metal accessories.

It mingles well with regular solutions like hydraulic oil, power steering oil, conventional and synthetic oil, etc. to provide proper renovation to the entire system.

Most important, it enters the radiators, finds out leaks, and seals it in several hours.

If you are searching for the best safe and fast car radiator leak detector, then this ATP AT-205 Re-seal is the perfect choice for you.

Usually, it takes 5 hours for a complete renovation. It does not require user petroleum distillates, and so it does not wear or damages the rubber gaskets and seals in any way.

Instead, it forms a thick layer over the leaking region and seals it efficiently. The ATP AT-205 Re-Seal Stop Leak is a plasticizer, which is used in the rubber industry to give hardness and flexibility to the rubber.

So, by its nature ATP AT-205 Re-Seal Stop Leaks provides intensive care to the engine by healing the wears in it.

2. Prestone AS145 Radiator Stop Leak

Prestone AS145 Radiator Stop Leak is an effective solution, which uses in heating cores, water pumps, and radiators to get a complete refurbishment.

Weight: 12.8 Oz

Model: AS145


  • Multiple usage
  • Quick performance
  • Deals with corrosion

It also contains active additives, which reduce the corrosion in every nook and corner of the pumps and radiators. The corrosive outer layer is scrubbed out by this radiator stop leak, and also it provides a complete metal finish to the radiator stop leak.

The Prestone AS145 radiator is the best choice to stop leak in your water pumps, heater cores, and radiator.

The usage of the Prestone AS145 Radiator Stop Leak in a radiator shall not hinder the regular process of the radiator but, it seals even large leaks even with the minimum amount of the solution.

As you know, pitting is the process of formation of minute pores and holes all over the surface of the metal. This Prestone AS145 Radiator Stop Leak reduces pitting significantly, thereby increasing the life of the essential parts of the radiator and its accessories.

     Prestone AS145 radiator stop leak is a bit expensive than others.

3. K-Seal ST5501 Multi-Purpose Stop Leak

K-Seal ST5501 Multi-Purpose Stop leak is a meticulously formulated fluid, which provides a satisfactory solution to the problem of leaks in the radiators.

Weight: 9.6 Oz

Model: ST5501


  • Easy to use
  • No draining
  • Doesn't need any flushing

It is usually mixed along with the coolant and just used in the conventional system. The antifreeze solutions take this K-Seal ST5501 Multi-Purpose Stop leak everywhere it goes and allows the stop leak to fix the problem.

It is one of the best car radiator stop leaks on the market. If you have leakage in the water pump, radiator, engine block, head gasket, then you can use this K-seal radiator stop leak.

It can even treat cracks and small fissures, which formed on the metal surfaces, free plugs, cylinder heads, heater cores, water pumps, etc. and more evidently, it provides a permanent solution to the leak issue.

Unlike any other stop leak solution, K-Seal ST5501 Multi-Purpose Stop leak does not require any flushing and draining after using it.

It is a professional, supportive solution which does not affect the rubber gasket and any other such tender elements inside the radiator. This product also holds a dominating position among various car enthusiasts.

     K-Seal ST5501 Multi-Purpose Stop leak might be clogged.

4. Bar’s Leak HG-1 Stop Leak

Bar’s Leak HG-1 Stop leak is a professional sealant, which eminently bonds with the abrasions, wear and tear of the metal, and the rubber parts inside the engine to reduce the risk of engine failure.

Weight: 2.65 lbs

Model: HG-1


  • Reduces the temperature
  • Quick resistance
  • Safe to use

It has ceramic substance and reinforcing fibers, which, when used in the regular system, combines with the proper fluid-like oils and coolants to form a durable sealant.

It not only seals the radiators and the coolant tanks but also heater cores, gas plugs, manifolds, and cylinder heads.

Moreover, it contains Xtreme fresh additives, which reduce the temperature of the coolant.

Bar’s Leak HG-1 Stop leak is also highly compatible with various engines involving diesel engines, gasoline engines, turbo and racing engines, etc.

Unlike any other product, bar’s Leak HG-1 Stop leak requires no thermostat removal or draining, and hence it holds a valuable position in our list of best stop leaks.

     Bar’s Leak HG-1 Stop leak’s cooling gases may not work sometime.

5. Dike Temporary Radiator Stop Leak

Most of the stop leaks, when used, shall lock the small passages in the coolant system.

Weight: 11 Oz

Storage: 4 gallon


  • Sealing better
  • Budget friendly
  • Inhibits the rust

Still, Dike Temporary Radiator Stop Leak shall not hinder the flow of any fluid inside the regular working system, especially in coolants.

It is very much gasket-friendly, and hence it does not wear rubber accessories. Instead, it forms a stiff coat over the worn rubber and corroded metal parts and therefore reinforces that engine part and stops the leak, if any.

Sometimes, the antifreeze solution shall seep into the engine through the worn metal parts.

When this solution enters other parts of the engine which works with other liquids, the result shall be worse.

Hence to avoid such unwanted deterioration of the engine, Dike, Temporary Radiator Stop Leak shall be used, which seals such damages in minimal time.

     Dike Temporary Radiator Stop Leak is a short-time solution.

6. Bar’s Leaks 1000 Stop Leak

Bar’s Leaks 1000 Stop leak is a standard solution to the leakage problem which has been put forward by the popular Bar leaks organization.

Weight: 1.05 lbs

Size: 7.4 x 2.9 x 1.4


  • Perfect components
  • Used with petroleum
  • Reduce the friction

The additives in the Bar’s Leaks 1000 Stop leak solution hinders many issues of the engine and renovates the compression and power, thereby increasing the performance of the engine substantially.

It can be used with all type of formulations which have been used for petroleum, high speed, high mileage formulas, but the result obtained after using the Bar’s Leaks 1000 Stop leak shall be the same and evident.

The natural wear inside the engines causes various issues like lower mileage, leakage, smoking, noise, etc. which can be easily eradicated by this effective formulation.

Moreover, it increases the oil pressure inside the engine and also reduces the friction of the moving parts. Thereby reducing the wear and tear of the engine and thus reducing noise.

     Bar’s Leaks 1000 Stop leak may reduce your gas mileage.

7. AlumAseal Stop Leaks

AlumAseal Stop leaks are a specially manufactured powder that used to seal the leaks in no time. It can seal the cooling system parts, metals, plastics in all parts of the engines.

Weight: 2.15 lbs

Model: ASBPI12-12PK


  • Removes your clog
  • Works with rubber and plastic
  • Highly sticky

Additionally, it is also a rubber friendly powder that not only cleans the worn rubber outs but also provides adequate lubrication to it.

Moreover, the corrosions in the metal parts and the damages in the moveable parts shall also be restored with this AlumAseal Stop leaks.

Coolants, which are made up of ethylene glycol, silicates, etc. can also be treated by the AlumAseal Stop leaks to get astonishing results.

Although AlumAseal Stop leak powder is highly viscous, it does not clog any cooling system and hinder any regular process. Water pumps can also be lubricated with this magical powder to get optimal results.

     AlumAseal Stop leak is inconvenient to use for few users.

8. J-B Weld DS-114 Radiator Stop Leak

J-B Weld DS-114 Radiator Stop Leak is an excellent working stop leak, which promotes sealing the leaks in the radiators of various vehicles like van, bus, tractor, etc.

Weight: 1.6 Oz

Model: DS-114


  • Quick fixation
  • Harmless substances
  • Economical price

When it is used with the coolant system, it does not inhibit its regular function, but lubricated and removes corrosion from the cooling system.

Moreover, the J-B Weld DS-114 Radiator Stop Leak is a non-toxic material which, when making contact with your body, does not cause any damage.

Folks who are vulnerable to allergies should be careful while handling this sealant. J-B Weld DS-114 Radiator Stop Leak is a powder, which should be administered to your vehicles through the coolant system.

Pour the contents into the coolant tank and run the car and make the coolant circulate properly. Run the engine until the leak stops. This handy product, which is also rubber friendly, thus proves to be very useful to all.

     User with allergies should be careful while handling J-B Weld DS-114 Radiator Stop Leak.

9. Bar’s Leaks 1186 Liquid Aluminum Stop Leak

Bar’s Leaks 1186 Liquid Aluminum Stop Leak is an eminent solution to all the leakage issues in the coolant system. Usually, a coolant is used to reduce the temperature in the engine of the vehicle.

Weight: 1.2 lbs

Model: 1186


  • Prevents overheating
  • Best for coolant system
  • Fast solution

Supporting that feature, Bars Radiator Stop Leak also prevents overheating of the engine, thereby reduces the temperature of the water.

It is a liquid solution with aluminum additives, which is very dense and viscous fluid, which seals the gasket leaks, heater core leaks, freeze plug leaks.

Usually, 20 minutes is the time required to seal the leaks but depends upon the wear and tear of the engine, and the time shall elapse to some extent.

     Bar’s Leaks 1186 Liquid Aluminum Stop Leak may absorbs heat.

10. Bar’s Leaks G12BP-7PK Radiator Stop Leak Powder

Bar’s Leaks G12BP-7PK Radiator Stop Leak Powder is a vital element that can thoroughly cleanse the radiator without any flaw. Usually, when a user finds his car to work improperly or when he finds a leak, he always intends to take his vehicle to a workshop.

Weight: 1.6 Oz

Model: G12BP-7PK


  • Repairs blocks
  • Control electrolysis
  • Active components

Before doing so, it is highly recommended to use this sealant powder, which forms a viscous liquid with the coolant and gets into the engine coolant system, thereby sealing all the leaks within minutes.

Apart from sealing the metallic parts of Bar’s Leaks G12BP-7PK Radiator Stop Leak Powder also aims at sealing the plastic, aluminum, heater cores, freeze plugs, etc.

Additionally, this sealant powder is also suitable for all types of coolants, which include silicate and non-silicate antifreeze.

     Bar’s Leaks G12BP-7PK Radiator Stop Leak is sticky.

For user's convenience we'd like to inform that, this particular product is unavailable right now, if it comes back to the market intimations will be given shortly for the customers by us.

What is the radiator stop leak?

A radiator stop leak is a gallate substance, that can stop the leak from your radiator. This substance is designed to seal the leak, which is appearing somewhere in the cooling system.

When you get to know the leak from your engine, then there are only two options to solve a problem, either replace your radiator, since it will take time and it will be expensive or else you can use a radiator stop leak and it comes like liquid, powder and tablet form.

It’s providing a protective layer to prevent the damage. There are so many radiator stop leaks in the sale which vary on price and strength.

How does radiator stop work?

  • Radiator stop leak sealants have a slightly bad reputation from the past few years, initially, the version forms a gallate layer that can seal the leak, at the same time it will clog up your engine.
  • Over the years the result becomes better. If you use a stop leak sealant correctly, it can steal your leak in your radiator, and on the other hand, you need to add the stop leak from time to time but it leads to replacing your radiator.
  • Sealants are made from various of a substance such as like, ceramic particles, metallic particles.
  • It circulates through the cooling system when the engine is running; the particles are forced into the plug and if you flush the coolant then the leak might return then you need to add stop leak sealant again.

The below video explains how to use the radiator stop leaks properly. I’m sure it will help beginners with their first use.


Hope this article has provided enough knowledge about the various types of sealants that are used to seal the leaks in the radiators and such other accessories. Any suggestion from this list shall be deemed to be the excellent pick as it possesses a significant unique feature.

Disclaimer: If you purchase any products in this post, we may receive a small commission. We promote only the products which we test and recommend. Read our affiliate disclaimer here.

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