Reviews

LAST UPDATED: May 31, 2019

Best Oil Stop Leak Additives: Protect Your Fuel System

Fixing an oil leak can be quick and easy thanks to oil stop leak additives

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PUBLISHED ON May 31, 2019

It is inevitable. When you consistently run a gas-powered engine, there are just some issues you know will come up sooner or later. One of the most annoying problems you're bound to encounter is an oil leak. Luckily, you can protect yourself before it happens with a simple oil additive. Here are our top picks for the best oil stop leak on the market.

  • Best Overall
    Lucas Oil 10278 Engine Oil Stop Leak
    Lucas Oil 10278 Engine Oil Stop Leak
    Summary
    Summary

    The best way to stop oil leaks without breaking the bank. Lucas Oil Stop Leak is a great option for stopping a leak and improving your vehicle's performance.

    Pros
    Pros

    Rejuvenates head gaskets and the rear main seal doesn't contain harmful solvents, reseals your fuel system, and increases oil pressure for added performance. 


    Cons
    Cons

    Lucas Oil doesn't work with diesel engines and cannot fix larger holes in the fuel system.

  • Best Overall
    Lucas Oil 10278 Engine Oil Stop Leak
    Lucas Oil 10278 Engine Oil Stop Leak
  • Best Value
    ATP AT-205 Re-Seal Stops Leaks
    ATP AT-205 Re-Seal Stops Leaks
    Summary
    Summary
    ATP is a universal fix and an excellent choice to stop oil leaks and to undo minor damage to the fuel system.
    Pros
    Pros
    An oil stop leak that works fast, revitalizes rubber seals, fixes more than the fuel system, and works with any engine.
    Cons
    Cons
    AT-205 can thin out the oil in your car and can sometimes generate blue smoke.
  • Best Value
    ATP AT-205 Re-Seal Stops Leaks
    ATP AT-205 Re-Seal Stops Leaks
  • Honorable Mention
    Liqui Moly Oil Leak Stop
    Liqui Moly Oil Leak Stop
    Summary
    Summary

    This formula provides a safe way to stop oil leaks in both diesel and gasoline engines with plastic or rubber shaft and valve stem seals.

    Pros
    Pros

    Significantly reduces engine noise and oil consumption. Prevents oil dilution. Great for manual and auxiliary transmissions.

    Cons
    Cons

    Not suitable for motorcycles with wet clutches and vehicles with automatic transmissions.

  • Honorable Mention
    Liqui Moly Oil Leak Stop
    Liqui Moly Oil Leak Stop

    It is inevitable. When you consistently run a gas-powered engine, there are just some issues you know will come up sooner or later. One of the most annoying problems you're bound to encounter is an oil leak. Luckily, you can protect yourself before it happens with a simple oil additive. Here are our top picks for the best oil stop leak on the market.

    Best Oil Stop Leak Reviews & Recommendations 2020

    Best Overall

    Lucas Oil is known for making reliable products. If you're looking for an oil stop leak that works without costing too much, they have the perfect solution. The 10278 Oil Stop Leak is excellent for stopping leaks and boosting your performance. 


    This product does not contain any harmful solvent or any corrosive properties. That means using this product won't have any long term effects on your engine. It's the only additive that actually improves your engine's performance. The successful resealing of your fuel system will reduce engine noise and oil consumption.

     

    While some additives can dilute your oil, Lucas manages to increase oil pressure, which is how you'll see your performance boost. Similar to other stop leaks, Lucas uses chemicals to reconditions deteriorated seals. It is compatible with all types of engine oils, including full synthetic oils. Lucas is a financially smart option that consistently gets great engine oil stop leak additive reviews.


    Much like all of the products on our list, Lucas Oil Stop Leak Additive isn't going to be able to fix every issue. Some holes are too big for the revitalized gaskets to seal correctly. Depending on what kind of seal issue you have, expanding the gaskets may have an adverse effect. Also, Lucas isn't compatible with diesel engines.

    Best Value

    What is the best engine oil stop leak? Look no further than the AT-205. This universal oil additive works incredibly fast and covers the widest range of fuel systems. Plus, the product is surprisingly cost-effective when used with smaller oil leaks. ATP makes the most comprehensive oil stop leak available. This product works with both gasoline and diesel engines. It is also compatible with all oils, including conventional, synthetical, and fully synthetic. It even stops leaks in other systems like transmission, hydraulic, and power steering systems.  


    This product is the best engine oil sealer. This is due to ATP's focus on revitalizing the rubber seal throughout the engine. The formula uses plasticizers to reshape and fix the rubber-based gaskets chemically. This chemical works great, and it is the same substance used to make the rubber flexible in the first place. ATP guarantees that AT-205 will start working in just five hours. You need to pour it in with the engine oil—be sure to follow the correct measurements. You can add it at any time in between oil changes without prep work. 


    While the formula works excellent at rejuvenating rubber, it isn't perfect for every oil leak situation. ATP has the possibility of thinning out your oil. This depends on what type of oil you use, but thinner oil can cause issues such as lower performance and worse gas mileage. It's also possible for this product to produce blue smoke. 

    Honorable Mention

    Liqui Moly offers a versatile anti-leak product that can be used on all diesel and gasoline engines. The fluid works by cleaning and regenerating rubber and plastic transmission seals, and consequently prevents oil stains from forming under the vehicle. The sealing action will last for about 370 to 500 miles, which gives you enough time to drive to a service station and get the leak fixed.


    The fluid improves engine oil stability at high engine speeds and its viscosity at high temperatures. It also improves engine performance by preventing excessive wear on transmissions, pumps, and compressors. The product is recommended for all manual and auxiliary transmissions. 


    Unfortunately, the product isn’t compatible with motorcycles with wet clutches. It’s also not suitable for vehicles with automatic transmissions, which limits its use to older vehicles and heavy-haul tractors with auxiliary transmissions.

    Honorable Mention

    This engine oil additive offers a simple solution for anyone who doesn’t have the time or money to drag their vehicle to a professional to fix stubborn engine oil leaks. The fluid is formulated with a sophisticated polymer sealing additive that creates a shield around the seal to protect it from wear caused by high temperatures and harsh conditions. It works to revitalize dry, shrinking rubber gaskets seals to make them soft and flexible. 


    With a dual-action formula, the product also goes to work on restoring the engine’s performance by cleaning the internal parts, reducing friction, and increasing horsepower. You should expect to see the results after driving for about 250 miles or three days after application. Installing it is relatively easy as long as you take care not to overfill it. 


    However, if you have an old engine, this product may not have enough punch to seal the damage. If it works, it will reduce the leak to a slight drip.

    Honorable Mention

    Depending on your situation, this additive can either fix your leak on the first try or not at all. When it is effective, however, it works amazingly well. BlueDevil does not include petroleum distillates, so it is in no way harmful to your engine or its components. This oil stop leak's top components make it quite effective and it delivers an enhanced seal. It is also completely safe for people and the environment. 


    One thing that makes BlueDevil stand out is its promise to permanently repair damage to shrunken or hardened seals. This is not to say that you'll never experience a leak again, but it is accurate as far as how long the rejuvenating effects will last on your seals.


    While this is one of the best engine oil additives to stop seal leaks, BlueDevil has some setbacks. Some customers have pointed out this formula isn't always effective with leaky gaskets, so depending on what seal you're having problems with, this might be an issue. While it does work with both gasoline and diesel engines, BlueDevil is not the best choice for synthetic oils.

    Honorable Mention

    The NO LEAK Engine Oil Stop Leak is designed to remedy engine leaks caused by dried, shrunken, or hardened rear main seals. The product works by expanding and softening the rubber in the seal to restore it to its original flexible shape. The fact that the fluid is ultra-thick and sticky helps to effectively seal the leaks. 


    NO LEAK is supposedly safe and compatible with all types of engines and will stop the engine from smoking. The product is also safe to use at any time, meaning that you don't need an oil change. You will find it somewhat easy to pour the fluid since it comes in a colorless bottle where one side has multiple indents that help you measure how much liquid you pour.


    However, you should be careful when handling the product and remember to wear gloves—it can cause skin irritation. Moreover, you may notice that it’s only good for repairing the rear main seal and may not be effective at repairing a leaking head gasket.

    Why Trust Us


    All of our reviews are based on market research, expert input, or practical experience with most products we include. This way, we offer genuine, accurate guides to help you find the best picks.

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    Benefits of Oil Stop Leak

    • Protect seals. Hardened or dried seals cause most engine oil leaks. One way that oil stop leak additives work is by revitalizing the rear main seal and head gaskets so that they return to their original size and flexibility. This minimizes the amount of oil that can seep through.
    • Save oil. Oil leaks will cost you money, harm the environment, and could potentially harm your vehicle. If you're losing too much of the fluid, replacing it often will add up quickly, and you may see a decline in engine performance.
    • Save money. Bringing your car to a garage to fix an oil leak can be a costly trip. Between time and labor costs, you can be spending hundreds just to diagnose the problem. For a fraction of the price, oil stop leaks can give you the same peace of mind.

    Types of Oil Stop Leak

    Particle-Clogging Formulas

    Initially, motor oil leak sealers were designed to clog the hole where oil was escaping. Each company had its own way of doing this—some of the earliest formulas used ground peanut shells as a block. The ground particles would flow to the leak and clog the area to save oil. The problem with these particles (as well as formulas which used sawdust, aluminum shavings, and other additives) is the long-term effects on a motor. They increased engine wear and would eventually do more harm than good.

    Absorbent Formulas

    The best engine oil stop leak additives you can buy are made to absolve into all the seals in the engine. Since these formulas do not have engine clogging particles, they don't come with the same harmful effects. The solvents expand and rejuvenate the gaskets and components to their original size and flexibility, so any leaks caused by gaps or deteriorated seals will once again be closed. Older formulas used petroleum distillates to achieve this result. Newer stop leak oil treatments use different chemicals as the distillate can further deterioration in the engine. 

    Top Brands

    ATP

    One of the most recognizable names in the automotive field is ATP. It first started in a Chicago plant back in 1955. Since then, it has gone from selling replacement transmission parts to producing a large selection of filter kits, repair kits, cables, flywheel and ring gears, cabin air filters and chemicals. The ATP AT-205 is a favorite among consumers.

    Bar’s Leaks

    One company that has been focused on helping customers be their own at-home-mechanic is Bar's Leaks. This U.S.-based company has over 70 years of experience with eliminating engine leaks. The company works with experts in their field to continually deliver high-level results with easy-to-use applications. The Stop Leak Concentrate is a best seller.

    Lucas Oil

    Forrest and Charlotte Lucas started their company in 1989 with the goal of producing high-quality lubricants and additives. Lucas Oil got its start in Corona, Calif. The couple quickly grew the company, which has established itself as a prominent fixture in the market. Lucas Oil Stop Leak is available in both gallons and quarts.

    STP

    Two of the best engine oil stop leak products available are Engine Stop Leak and High-Mileage Stop Leak, produced by STP. This company is headquartered in Connecticut. In the past 60 years, it has become one of the most trusted names in automotive care. 

    Oil Stop Leak Pricing

    • Under $25: To test out whether your issue can be fixed with oil stop leak, you should invest in the smaller options. For under $25, you can get any of the best engine oil stop leak additives in small quantities like 8 ounces and 24 ounces.
    • Over $25: For continued protection, most oil stop leak additives are available in bulk quantities. This can include gallons, packs of 32-ounce containers, or even bundles of gallon containers. Larger quantities are a good option if you know your issue can be fixed with an additive.

    Key Features

    Plasticizers

    Since the most common cause of an oil leak is gaps between the various seals, having a stop leak additive that rejuvenates the seals is essential. This is usually a chemical process that will bring cracked rubber pieces back to their original sizes. Each company will have a different way to achieve this, but chemicals that are most effective are called plasticizers.

    Petroleum Distillates

    A common chemical used to revitalize gaskets is petroleum distillates. The issue with this chemical is that it can have adverse long-term effects on your engine. It can wear out parts of your fuel system while it works to fix others. Over time, this can become more expensive than the original issue. Petroleum distillates are something you want to avoid in a good stop leak additive.

    Other Considerations

    • Compatibility: Possibly the most important factor when considering an oil stop leak is whether or not it’s compatible with your vehicle. Some formulas will not be able to work with diesel engines, and others will not be able to work with synthetic oils. Every product will list the types of engines and fuel system they're compatible with.
    • Efficiency: For an engine oil stop leak to be cost efficient will depend on how much additive is required to add and how long it lasts. Additives that require a smaller amount to be mixed with your engine oil will be more efficient long term. An oil stop leak that will keep your seals revitalized for more extended periods will also save you money in the long run. 
    • Activation: Allowing your engine oil stop leak to activate fully is essential to fixing leaks. The additives will start to activate once added into the engine oil, and usually, they require a few hours. However, even after sitting for the required amount of hours, the solution may need to run through your fuel system for 100 or more miles to reach its full potential.

    Best Oil Stop Leak Reviews & Recommendations 2020

    Best Overall
    Lucas Oil 10278 Engine Oil Stop Leak

    Lucas Oil is known for making reliable products. If you're looking for an oil stop leak that works without costing too much, they have the perfect solution. The 10278 Oil Stop Leak is excellent for stopping leaks and boosting your performance. 


    This product does not contain any harmful solvent or any corrosive properties. That means using this product won't have any long term effects on your engine. It's the only additive that actually improves your engine's performance. The successful resealing of your fuel system will reduce engine noise and oil consumption.

     

    While some additives can dilute your oil, Lucas manages to increase oil pressure, which is how you'll see your performance boost. Similar to other stop leaks, Lucas uses chemicals to reconditions deteriorated seals. It is compatible with all types of engine oils, including full synthetic oils. Lucas is a financially smart option that consistently gets great engine oil stop leak additive reviews.


    Much like all of the products on our list, Lucas Oil Stop Leak Additive isn't going to be able to fix every issue. Some holes are too big for the revitalized gaskets to seal correctly. Depending on what kind of seal issue you have, expanding the gaskets may have an adverse effect. Also, Lucas isn't compatible with diesel engines.

    Best Value
    ATP AT-205 Re-Seal Stops Leaks 

    What is the best engine oil stop leak? Look no further than the AT-205. This universal oil additive works incredibly fast and covers the widest range of fuel systems. Plus, the product is surprisingly cost-effective when used with smaller oil leaks. ATP makes the most comprehensive oil stop leak available. This product works with both gasoline and diesel engines. It is also compatible with all oils, including conventional, synthetical, and fully synthetic. It even stops leaks in other systems like transmission, hydraulic, and power steering systems.  


    This product is the best engine oil sealer. This is due to ATP's focus on revitalizing the rubber seal throughout the engine. The formula uses plasticizers to reshape and fix the rubber-based gaskets chemically. This chemical works great, and it is the same substance used to make the rubber flexible in the first place. ATP guarantees that AT-205 will start working in just five hours. You need to pour it in with the engine oil—be sure to follow the correct measurements. You can add it at any time in between oil changes without prep work. 


    While the formula works excellent at rejuvenating rubber, it isn't perfect for every oil leak situation. ATP has the possibility of thinning out your oil. This depends on what type of oil you use, but thinner oil can cause issues such as lower performance and worse gas mileage. It's also possible for this product to produce blue smoke. 

    Honorable Mention
    Liqui Moly Oil Leak Stop

    Liqui Moly offers a versatile anti-leak product that can be used on all diesel and gasoline engines. The fluid works by cleaning and regenerating rubber and plastic transmission seals, and consequently prevents oil stains from forming under the vehicle. The sealing action will last for about 370 to 500 miles, which gives you enough time to drive to a service station and get the leak fixed.


    The fluid improves engine oil stability at high engine speeds and its viscosity at high temperatures. It also improves engine performance by preventing excessive wear on transmissions, pumps, and compressors. The product is recommended for all manual and auxiliary transmissions. 


    Unfortunately, the product isn’t compatible with motorcycles with wet clutches. It’s also not suitable for vehicles with automatic transmissions, which limits its use to older vehicles and heavy-haul tractors with auxiliary transmissions.

    Honorable Mention
    Bar’s Leaks Engine Repair

    This engine oil additive offers a simple solution for anyone who doesn’t have the time or money to drag their vehicle to a professional to fix stubborn engine oil leaks. The fluid is formulated with a sophisticated polymer sealing additive that creates a shield around the seal to protect it from wear caused by high temperatures and harsh conditions. It works to revitalize dry, shrinking rubber gaskets seals to make them soft and flexible. 


    With a dual-action formula, the product also goes to work on restoring the engine’s performance by cleaning the internal parts, reducing friction, and increasing horsepower. You should expect to see the results after driving for about 250 miles or three days after application. Installing it is relatively easy as long as you take care not to overfill it. 


    However, if you have an old engine, this product may not have enough punch to seal the damage. If it works, it will reduce the leak to a slight drip.

    Honorable Mention
    BlueDevil Oil Stop Leak

    Depending on your situation, this additive can either fix your leak on the first try or not at all. When it is effective, however, it works amazingly well. BlueDevil does not include petroleum distillates, so it is in no way harmful to your engine or its components. This oil stop leak's top components make it quite effective and it delivers an enhanced seal. It is also completely safe for people and the environment. 


    One thing that makes BlueDevil stand out is its promise to permanently repair damage to shrunken or hardened seals. This is not to say that you'll never experience a leak again, but it is accurate as far as how long the rejuvenating effects will last on your seals.


    While this is one of the best engine oil additives to stop seal leaks, BlueDevil has some setbacks. Some customers have pointed out this formula isn't always effective with leaky gaskets, so depending on what seal you're having problems with, this might be an issue. While it does work with both gasoline and diesel engines, BlueDevil is not the best choice for synthetic oils.

    Honorable Mention
    NO LEAK Engine Oil Stop Leak

    The NO LEAK Engine Oil Stop Leak is designed to remedy engine leaks caused by dried, shrunken, or hardened rear main seals. The product works by expanding and softening the rubber in the seal to restore it to its original flexible shape. The fact that the fluid is ultra-thick and sticky helps to effectively seal the leaks. 


    NO LEAK is supposedly safe and compatible with all types of engines and will stop the engine from smoking. The product is also safe to use at any time, meaning that you don't need an oil change. You will find it somewhat easy to pour the fluid since it comes in a colorless bottle where one side has multiple indents that help you measure how much liquid you pour.


    However, you should be careful when handling the product and remember to wear gloves—it can cause skin irritation. Moreover, you may notice that it’s only good for repairing the rear main seal and may not be effective at repairing a leaking head gasket.

    Tips

    • If using a stop engine oil leak does not fix your issue, you should see a mechanic for diagnosis. Losing oil can cause severe damage, and you’ll want to address the problem as soon as possible. 
    • Be sure to read all the product information to understand the proper quantities required for mixing stop leak additive with your oil. 
    • Before you buy any additive to stop an oil leak, find out what type of oil you use. Not every product can be used with all the different types of oils, so it's essential to be aware of your specific needs. 
    • Some oil additives include harmful chemicals. These additives can do long-lasting damage to your vehicle's engine. Avoid any oil stop leaks that use petroleum distillates and look out for products that are certified by the EPA.

    FAQs

    Q: How do I use oil leak stop fluid?

    A: Thankfully, oil leak stop fluid is incredibly user-friendly. All you have to do is mix it with the proper oil for your vehicle. The most important part is measuring the ratio of additive to oil, which can be found in the directions to your stop leak solution.

    Q: Is oil stop leak bad for your engine?

    A: Some old oil stop leak formulas were bad for your engine. However, over time, companies improved upon their formulas, and most products available today shouldn't have any adverse effects. You could harm your engine if you use an incompatible additive, though, so make sure you read up on the products.

    Q: What if the oil stop leak doesn’t work?

    A: While oil stop leak additives are great, they cannot fix everything. If you use it and see no improvement, you need to get your car correctly diagnosed so that you can correct whatever the root cause may be.

    Q: Can oil stop leak be used instead of going to a mechanic?

    A: The answer to this depends on what the cause of your oil leak is. The fix oil leak additives revitalize gaskets and seals to close any gaps that may be present. If you have a severe hole or a defect somewhere else, then using a stop leak will not be a permanent solution.

    Final Thoughts

    If you’re looking for universal protection, then Lucas Oil 10278 Engine Oil Stop Leak is the best engine oil stop leak product on the market. 

    Customers who want to stop leaks and save money should use ATP AT-205 Re-Seal Stops Leaks