The 5 Best Radiator Stop Leak Products – [Reviews & Rankings]

Do radiator stop leak products work? This is one of the most controversial subjects by vehicle owners today.

While some experts are opposed to the use of radiator stop leaks, these products are actually great at sealing small and large cracks in the cooling system of the engine (Source).

However, the performance of such products will depend on whether you have used the right product and how you have used it.

This is probably why some people think that these products do not work. For such a product to work, you just have to buy the right one and use it correctly.

In this regard, there are several things you need to consider while shopping for the right radiator stop leak. For instance, you need to consider the type of stop leak, engine capacity, size of the leak, and your radiator material.

If you are not sure if you have a leak, you may need to use a leak detector first. If you want to avoid leaks or other issues with your diesel truck, consider buying a diesel compression tester. 

What Is A Good Radiator Stop Leak?

K-Seal ST5501 Multi-Purpose Coolant Leak Repair is an effective one-step solution to sealing a leaky radiator. All that’s required is shaking and pouring the coolant with no draining or flushing required. It provides a permanent fix to leaky head gaskets, freezes plugs, and cylinder heads as well.

How Much Does A Radiator Stop-Leak Product Cost? 

You can expect them to be in a price range of $5 to $30. The difference in price range is mainly based on the type of manufacturer, features, and durability of the product.

Remember to choose cooling-system-leakage-stopping products from reputed brands only, as plenty of fake ones are available at a very low price. They might damage your car radiator and other components in your vehicle.

How Does A Radiator Stop Leak Product Work? 

When you pour a stop leak sealant inside the desired place, it instantly shrinks the particles that are leaking by 15 percent at most. As for leaks present outside the radiator, the particles reach the area of the leakage and accumulate where the seepage is occurring.

Therefore, it lets you stop leakage internally and externally. For leaks that occur inside, the stop leak product particles undergo combustion of up to 5000 degrees inside the running engine of the car. This causes the product to harden inside, thus sealing small cracks and leakages.

Additionally, stop-leak products can also be used for eliminating seeping coolants, which can contaminate the crankcase otherwise. When poured inside the coolant system, it seals the cracks in the component made of aluminum and cast iron, stopping the leakage.

Comparing The Best Radiator Stop Leak

1. K-Seal ST5501 Multi Purpose One Step Permanent Coolant Leak Repair – Best Overall

Are you looking for a more permanent coolant leak fix in your car or air conditioner? Well, you should consider buying the K-seal ST5501 Coolant Leak Repair liquid. Not only is this product Affordable, but it is also relatively easy to use. All you need to do, in this case, is buy the radiator stop leak and add the right amount to the coolant in your car. This product works very fast to give you the permanent leak repair you are looking for.

Once you have mixed K-seal with the coolant, you should just run the engine as normal. The product is designed to seek the leaking pints in the cooling system and fix them automatically. You can rest assured that the product has been tested scientifically and found to be effective at what it is meant to do. This is probably why the AA, an international roadside rescue company, uses it today.

Once the leaking point is identified, the relatively large microfibers in the liquid get to work in seconds, meshing up and sealing the gap. The product has been proven to be effective at sealing leaks up to 0.635 mm wide.

2. Genuine GM (12378255) Fluid Cooling System Seal Tablet – The Best Tablet Radiator Stop Leak

It can be very discouraging to have a vehicle that is losing coolant faster than it should, but the mechanics cannot find the leakage. Most of them will even recommend radiator replacements, which are known to be very expensive. If you are in such a situation, there is no need to panic; just buy the Genuine GM Cooling System Seal Tablet.

With this product at your disposal, you do not even need to pay a mechanic to diagnose or repair the leak. The inexpensive radiator stop leak will find the leaking point and seal it automatically in a matter of minutes. The process is really simple and you can do it yourself at home. Just crush 3 to 4 Genuine GN Fluid Cooling System Seal Tablets. Once you have crushed them, add the powder into the coolant reservoir in your car and run the engine.

The manufacturer does not say whether the product is good at sealing leaks in other parts of the cooling system. However, some users have tried it and found it to be effective at sealing cracks in the head gasket.

3. Bar’s Leaks 1186 Liquid Aluminum Stop Leak – Best Value for Your Money

Bar’s is among the reputable radiator stop leak manufacturers in the industry today. As a matter of fact, products by this brand are some of the most preferred by vehicle owners across the globe. The Bar’s Leaks 1186 Liquid Aluminum Stop Leak, for instance, has been proven to seal almost any leakage in your vehicle

In this regard, the product may be used to repair leaks in the radiator as well as in the other parts of the cooling system, such as the head gasket and the heater cores. Additionally, this product is effective at repairing freeze plug leaks in all vehicles. It is this versatility that makes car owners think that the product is worth every penny. You may choose to buy the product as a single bottle or as a pack of 6, in which case you get an even better value for money.

4. Dike Temporary Radiator Stop Leak – Best for All Engine Capacities

If not addressed in time, a coolant leak can have a devastating effect on the engine.  Initially, the leakage will predispose the engine to overheat. At this point, you can repair the leakage or ignore it and risk it all. The Dike Temporary Radiator Stop Leak is an affordable, highly effective, and easy to use solution for a leaking radiator.

The product does not have any compatibility issues and may be used on any vehicle. For best results with this radiator stop leak solution, you should the right amount of the liquid into the radiator and secure the radiator cap in place. You should then start the engine and leave it running for about 15 minutes. If you will be using the product in a larger engine, you will need more of the Dike Temporary Radiator Stop Leak.

If you are looking for tire safety you should consider buying the right TPMS tools. Using a TPMS helps to maintain good tire health, fuel efficiency, and improve vehicle safety.

5. Bar’s Leaks 1150 Grey Cooling System Repair – The Quick Solution

Now that you have an antifreeze coolant in your car, draining it can be inconvenient and costlier. Get a radiator stop leak that works with pre-existing antifreeze coolant, such as the Bar’s Leaks 1150 Grey Cooling System Repair. In this regard, the product does not require you to flush out the antifreeze coolant in your radiator. However, you need to ensure that complies with manufacturer specifications.

While this case, you may need to clean and flush dirty and clogged cooling systems before using this product. With all the requirements met, you should add the right amount of the product into the radiator, start the engine and let it idle for about 15 minutes. Basically, this product will solve your coolant leakage problem in less than 20 minutes.

Will Radiator Stop Leak Harm My Engine?

If you have properly diagnosed that your vehicle leak is coming from your radiator, then a Radiator Stop Leak can help improve the function of your radiator by sealing it. If you misdiagnose the issue or use a Stop Leak improperly, then you may encounter issues down the road.

How Are Radiator Stop Leak Products Used Safely? 

Radiator stop leak and seal products are meant to stop leakages as claimed. However, some users do find them skeptical. Perhaps they heard it from someone else, or they used it themselves and could not get the desired results.

Here’s why they did not get the results:

The application of such products is not universal. Moreover, they need to be used in certain conditions so that they can help improve the life of your car radiator, instead of ruining it. Furthermore, to ensure a leak-proof radiator, you need a high-quality and genuine product.

You can avoid any risk of damage if you follow the instructions given on the product bottles carefully. To make it easier for you to understand, go through the following tips to ensure safety for your radiator and engine while using anti-leak products.

• Use Stop Leak Products Only For Small To Moderate Slits – You cannot use this product to seal large cracks in your radiator, or it can be counterproductive. Take your vehicle for repair if a large crack is involved.

• Choose Authentic Products Only – You might think of getting a cheap product that you have never heard of in the first place. Never make that mistake, as such products are fake and will only damage your car further.

• Use Stop Leak Products Only On Clean Systems – If you are applying the seal product without draining the contaminated or dirty oil, transmission fluid, or coolant first, then you are just making it worse. You need a clean area to apply the seal to ensure the safety of your car or similar vehicle.

How to Ensure Your Radiator Stops Leaking

To ensure that the product solidifies to prevent the leakage, you might need to run the engine of the vehicle for at least half an hour. That time will seal the leakage and let you have your desired result.

High-quality stop-leak products do not plug the heater core either, as the tiny particles can easily penetrate through the mesh screen of 24-gauge size. Trucks and large cars use this standard size for the mesh screen in the heater cores.

That way, the coolant system is not affected as it efficiently stops the heater core leaks. However, you do need to keep the engine core at a hot temperature to stop the leakage successfully.

Some stop-leaking products are in the form of pellets that you need to first dissolve with the help of hot water before using.

Things You Must Know Before Buying a Radiator Stop Leak

Is your radiator or any part of the water cooling system leaking? Use the right radiator stop leak product to seal the crack and prevent the leakage temporarily.

However, you need to realize that stop leaks are not a permanent solution; you still need to take the car to your preferred repair shop for the broken part to be repaired or replaced.

While this is the case, using the right product correctly will give you extra mileage on the broken component. However, you must have realized that there are numerous radiator stop leak products in the market today.

For you to choose the right product from the hundreds of stop leak products available today, you need to know what you are looking for. Here are some of the main considerations you need to make, in this regard:

1. Type of Radiator Stop Leak

If you have been browsing the internet trying to find out which is the right product, you must have realized that stop leaks for radiators come in different types and forms.

While they are all designed to seal a leak on your radiator or another part of the cooling system, not all of them are ideal for different repair constitutions. While shopping for the right product, here are the main radiator stop leak types you should consider:

• Radiator stop leak tablets
• Radiator stop leak liquids
• Radiator stop leak powders

Regardless of the type you decide to buy, it is important that you follow manufacturer instructions while adding the product to your radiator. Most of the problems associated with these products today are as a result of not using them correctly.

For instance, you should only add the recommended amount of the product to your coolant. Adding more will not make the stop leak more effective. If anything, it could end up damaging the engine. As such, you should only use the right product and in the right way for the best results.

2. Location of the Leak

What part of the engine cooling system is actually leaking? There are some cases when you just cannot tell what part of the cooling system is leaking. If the coolant is running low faster than it should, you probably have a leak. If you cannot tell where the crack is located, it is advisable to get a product that will stop the crack from growing.

This will buy you time until you take the care to a mechanic for a thorough diagnosis. Some stop leak products, such as the Genuine GM Fluid Cooling System Seal Tablets, are good at stopping leaks from growing. Such products are great when used on cracks that have just begun.

3. Radiator Material

Any skilled mechanic can ascertain the fact that not all radiators available today are made of the same material.  While aluminum is a product that is commonly used to make radiators, you should not assume that your radiator is made of aluminum. Other materials that are commonly used to make car radiators today include mild steel, cast iron, and stainless steel.

What you need to know is that most radiator seals are meant to work on certain materials. If used on the wrong materials, the product may not work and may lead to more engine problems. Therefore, you need to ascertain what material your radiator is made of before choosing the right radiator seal.

4. Size of the Crack

How large is the leak you are trying to seal with a radiator stop? You can easily tell the size of the crack by the rate you are losing the coolant. Basically, most of the stop leak products available today are meant to seal small leaks. However, there are some good products that are specifically formulated to repair large cracks in your cooling system. Make sure that you have chosen the right one based on the size of the leak.

5. Engine Capacity

This is something that many vehicle owners fail to consider while shopping for the best radiator stop leak. While shopping for the right product, you need to consider the capacity of the engine in your car as well. In this regard, there are certain stop leak products that should only be used on light-duty trucks while others are meant for use in heavy-duty engines.

Ready To Buy The Best Radiator Stop Leak Products?

Your car is leaking the coolant, but the mechanics cannot find the problem. Does this sound familiar? In other cases, the leak may be visible, but relatively small. If the cooling system in your vehicle is leaking, the best fix would be to get the leaking component replaced.

However, radiator replacements can be really expensive. If you do not have the money to replace your radiator yet, you should invest in the right radiator stop leak.

There are some products that have been proven to seal coolant leaks permanently. Others will only give you a temporary solution as you have the radiator replaced.

Is your engine showing signs of engine stuttering? Consider buying the fuel injector cleaning kits. They keep the fueling system as clean as it can get, removing any obstructions from the channels.

At last, If you want to properly diagnose leaks and other issues, take a look at our review of refrigerant recovery machines. These tools help you determine the next step in fixing.