Best Oil Stop-Leak Additives: Protect Your Fuel System

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

byNoelle Talmon| UPDATED Jan 26, 2022 3:12 PM
Best Oil Stop-Leak Additives: Protect Your Fuel System

Oil stop leaks are designed to stop and seal leaks caused by general wear and tear in your vehicle's engine. Over time, the engine will start to degrade, and you will have to repair it. The good news is that a high-quality oil stop leak is a relatively easy solution for certain issues. It can stop leaks as well as prevent them from occurring. There are many options available in stores and online, so it can be challenging to choose the right one. Check out the list below for some of the top options currently available.

Best Overall

Lucas Oil 10278 Engine Oil Stop Leak


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.

  • Rejuvenates head gaskets and the rear main seal
  • Doesn't contain harmful solvents
  • Reseals your fuel system
  • Increases oil pressure for added performance 
  • Lucas Oil doesn't work with diesel engines 
  • Cannot fix larger holes in the fuel system
Best Value

ATP AT-205 Re-Seal Stops Leaks


ATP is a universal fix and an excellent choice to stop oil leaks and to undo minor damage to the fuel system. 

  • An oil stop leak that works fast
  • Revitalizes rubber seals
  • Fixes more than the fuel system
  • Works with any engine
  • AT-205 can thin out the oil in your car 
  • Can sometimes generate blue smoke
Honorable Mention

Liqui Moly Oil Leak Stop


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.

  • Significantly reduces engine noise and oil consumption
  • Prevents oil dilution
  • Great for manual and auxiliary transmissions
  • Not suitable for motorcycles with wet clutches and vehicles with automatic transmissions

Best Oil Stop Leaks Reviews & Recommendations 2021

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Our reviews are driven by a combination of hands-on testing, expert input, “wisdom of the crowd” assessments from actual buyers, and our own expertise. We always aim to offer genuine, accurate guides to help you find the best picks.

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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 recondition 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.

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. 

Our Verdict

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.

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 that use 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. 

Key Features


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.


  • 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.
  • $25 and up: 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.


  • Consult a mechanic if the problem isn't solved after you use an oil stop leak. If your engine loses a lot of oil, it can sustain a lot of damage. It's vital that you diagnose and fix the problem sooner rather than later.
  • Read the product description to make sure you use the proper amount when you mix the oil stop leak with your oil.
  • Determine whether your vehicle uses conventional or synthetic oil before making a purchase. While many can be used with different types of oils, it's important that the product is compatible with your particular oil.
  • 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.


Q: How do I use oil leak stop fluid?

Oil stop leaks are easy to use. Simply mix it with the oil you traditionally use in your car or truck. Make sure to properly measure the amount you need. You can find this information on the container of the stop leak fluid.

Q: Is oil stop leak bad for your engine?

Some old-fashioned oil stop leaks were not good for engines. Modern technology has caused the creation of better formulas, so today's products should work just fine. However, if you use the wrong oil stop leak, it can cause engine damage, so make sure to do your research and choose the proper additive.

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

Oil stop leaks are a great solution, however, they aren't designed to fix all issues. Should you use a product and don't notice an improvement, take your vehicle to a mechanic so he can properly diagnose the problem.

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

Maybe. That depends on what is causing the oil leak. Oil stop leaks are designed to revitalize gaskets and seals to minimize gaps that cause leaks. However, if you have a large hole or a lot of engine damage, an oil stop leak will not solve the problem.