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Will Stop Leak Products Damage My Car? All You Need to Know

Will Stop Leak Products Damage My Car? All You Need to Know

While stop leak products are great options for minor radiator leaks, there are still some people wondering, “will stop leak products damage my car?” The short answer is no. Most stop leak products should not cause any damage through vehicles; however, to get effective results, you need to follow the exact instructions on the products. You're recommended to use the stop leak products only when you're dealing with minor leaks.

Your vehicle contains a lot of important fluids that perform certain jobs. Over time of use, these fluids might leak from certain weak points and through small or large cracks on the pathways.

Auto Repairs Are EXPENSIVE

It is critical for you as a driver to keep an eye for any internal or external leaks, whether they are minor or major. Of course, when dealing with major leaks, you won't have any other choice than to reach out to your mechanic and have him inspect the major leak and fix it. However, when dealing with minor leaks only, you can rely on simple products like stop leak products to repair the seals.

This article walks you through some details about these stop leak products and helps you determine whether these products can damage your car or not.

What is the stop leak product?

Radiator leaks are very common products recommended and used by automotive experts to seal minor internal leaks in your vehicle’s radiator. While most customers typically use these products on used radiators, manufacturers might use these stop leak additives to improve the seals of new vehicles radiators.

Radiator stop leaks contain several components that he might see some of them in certain products but not in old products secured typically; most radiator leaks might contain one of the following components:

  • Ceramic particles and fiber
  • Copper, iron, or aluminum particles
  • Sodium silicate

Obviously, when looking at the ingredients of your current radiator stop leak, you might not find all mentioned components because manufacturers and third-party companies designed them from different chemical mixtures. In addition, you might even find other components that are not commonly found on all radiator leak additives.

How do stop leak products work?

Before we dive into the details about “will stop leak products damage my car?” It is important that we first understand how these stop leak products work in the first place.

Although each stop leak product might work slightly differently, the same principle applies to most radiator stop leak products. In general, is small particles of ceramic, copper, iron, or aluminum harden whenever there is a leak or crack in the seals.

Aside from fixing radiator leaks, sometimes stop leak additives are useful for fixing the heater core in your engine. If you don't already know, the heater core is the small component that looks like a radiator responsible for providing famous reheat for your engine during winter conditions. Unfortunately, these heater cores are also susceptible to cracks causing minor leaks that need to be fixed. By taking advantage of the stop leak products, mechanics eliminate and reduce expensive repair costs to change or replace the heater core.

Usually, the radiator stops leak particles running through the earlier pathways and finds gaps or cracks to fill between them. Once the stop leak additives find the gaps, they harden quickly and create Semi-permanent sealed. Typically, the stop leak products are considered durable enough and provide similar characteristics to the brand-new radiator.

Furthermore, most radiator stop leak products contain sodium silicate, a material that does not melt until the pathway reaches a temperature between 212 and 221-degrees Fahrenheit. With that characteristic, the sodium silicate helps reach very hot locations in your engine to provide enough sealing and takes care of cracks in areas with extreme temperatures.

Will you stop leak products damage my car?

According to automotive experts, using stop leak products does not have any risk of damaging your vehicle. However, they might not be very effective when you're dealing with major leaks. In other words, it is always recommended that you try a stop leak product if the leaks are minor and if the leaks reach a certain severity threshold, you need to consult your mechanic and check whether you can repair the component or replace it if needed.

Keep in mind that the effectiveness of the stop leak depends on the brand and the ingredients involved in the mixture of this stop leak. In other words, before you decide on a certain stop leak product, you must perform enough research about the main pros and cons of this certain product. Furthermore, you mustn't only focus on the cheapest product for this type of repair because sometimes you might not find the best characteristics out of this product just because it has the lowest price.

Finally, to get the best advantage of these stop leaks, you need to follow the instructions indicated on the product. For example, Bar’s Leaks products recommend that you apply their product on a clean fluid system. Therefore, when you know that your current radiator fluid is not in good condition and contains a lot of debris or contaminants, the product will not work properly, which means that you need to perform a radiator flush before using the stop leak product.

When can a stop leak harm my vehicle?

As we indicated earlier, most stop leaks should not be harmful to your vehicle. However, it is important to note that certain stop leak products are designated for the radiator, not for the engine. Thus, it is important for you as a driver to review what each subject product should be used for.

For example, the radiator stop leak is not designed to use hot units like the head gaskets. Therefore, you won't see any benefits from using this type of stop leak in your engine. Instead, you might even deal with some damages that impact the engine instead of fixing it.

The good news is that the market is filled with many Stop leak products for every component in your vehicle. All it takes for you is to perform the right research and read carefully through the instructions to determine which product to use for and which component in your car. It doesn't hurt to have a conversation with your mechanic about whether to use this tag to stop the leak or not.

It is important to highlight here that some older stop leak products might cause damages to your vehicle's engine or other important components. However, these older products are not available anymore unless you're searching for one of them. Therefore, it is good to research your next stop leak product that you look for products equipped with modern technologies to fix the leaks rather than the older ones.

Is block sealer bad for your car?

Stop leak products target leaks in the radiator, but there are also many designed purposely to take care of any damage in the engine. For example, some people are hesitant about using engine block seals, thinking they might damage the engine.

The good news is that most of these stop leak products should not cause any damage to your car, assuming that you follow the same instructions indicated on the product. But, again, relying on block sealers to take care of major engine leaks will not be effective because they're not designed to take care of these major damages.

Is Lucas's stop leak bad for your engine?

No, Lucas stop leak is a great product, as indicated by many customers who tried it. However, it is important to note that there are different viscosity levels in the Lucas stop leak product, which means that you must read the instructions carefully and refer to your vehicle owner’s manual to get an idea about which product should work for your car.

How long does it take for a stop leak to work?

According to experts, typically, you might need between 15 and 30 minutes to stop leaked products from working. However, this timeframe might differ significantly depending on the product you're using and the severity of the leak.

Do Bar’s Leaks work?

Of course! If you are dealing with minor car leaks, Bar’s Leak products are great options for you. However, when these leaks become more between a moderate to a Major League, you must follow up with your mechanic and determine other alternatives to take care of the problem rather than relying on simple products like these stop leaks.

Can I put a stop leak in my coolant reservoir?

Yes, according to the recommendations of automotive experts, you can use Bar’s Leak to stop leaks in your coolant reservoir but, it is also recommended that you have a conversation with your mechanic to confirm whether you're a specific vehicle will benefit from using such products or not.

What is the best cooling system to stop the leak?

As we indicated earlier, there are plenty of available stop leak products in the market. However, you must go through each product and understand the main pros and cons compared to your goals and budget before making a final decision.

In general, here's our 2021 list of best cooling system stop leak products:

  • 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
  • Bar’s Leaks Intake and Radiator Stop Leak
  • Liqui Moly Radiator Stop Leak

What are the best oil stop leak products?

As we indicated earlier, the mentioned stop leak products in the previous section are designated for fixing any leaks in the cooling system, which means they're not useful for the engine. Therefore, here's a list of the 2021 best oil stop leak additives for your engine:

  • Lucas Oil 10278 Engine Oil Stop Leak
  • ATP AT-205 Re-Seal Stops Leaks
  • Liqui Moly Oil Leak Stop
  • Bar’s Leaks Engine Repair
  • Bluedevil Oil Stop Leak
  • NO LEAK Engine Oil Stop Leak
  • Pro-Seal by Hapco
  • CD-2 Stop Leak for Engine Oil
  • Seallube
  • STP High Mileage Oil Treatment, Formula for Cars & Truck, Stop Leak

As you might notice, the same companies might produce different types of soft league products focusing on different components in your car. Therefore, you must focus a little bit on determining whether a certain product targets the engine or the cooling system, or any other component in your car before use.


You need to maintain proper fluid levels in your car to prevent damages. Sometimes minor leaks might result in significant issues in your car that might cost you the value of major components like the engine.

Luckily, there are plenty of aftermarket stop leak products that take care of minor leak spots. Unfortunately, they're not very effective for moderate to major leaks. As a result, many drivers are still hesitant about relying on stop leak products to resolve their vehicle's minor leaks. The good news is that automotive experts confirmed that there is no risk of using such products if you're following the instructions in detail.

It is important to note that if your car has major leaks that damage important components like the engine or the transmission, you think twice before paying a penny to resolve these problems. Instead, you might want to sell your vehicle and use the money towards a better car with no major issues.

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