Best Oil Stop-Leak Additives: Protect Your Fuel System

Best Overall: Lucas Oil 10278 Engine Oil Stop Leak

Best Value: ATP AT-205 Re-Seal Stops Leaks

Honorable Mention: Liqui Moly Oil Leak Stop

Best Quantity: Lucas Oil 10279 Engine Oil Stop Leak 1 Gallon

Most Versatile: No Leak All in One Stop Leak

Oil stop leaks are something we've all spent plenty of money on. Over the years, we've developed a good sense of what's good and what isn't. Still, we've taken the time to do the homework and see what the rest of the world has to say. By reading real customer reviews and dissecting product descriptions, we are able to confirm that anything on this list is worth your consideration.

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.

While the list above is certainly good enough for most, it doesn't give you the tools you need to make an educated decision. There's a lot to consider when shopping for oil stop leaks, and this buying guide is here to help you familiarize yourself with them. After reviewing it, you'll have a much better idea as to of which works best for your situation.

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.

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. 

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.

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.

For under $25, you can get any of the best engine oil stop leak additives in small quantities, like 8 ounces and 24 ounces. Spending more often means getting a larger bottle or even a multi-pack. However, the cost of stop leak can quickly surpass the cost of a repair. If you find yourself buying bulk for a single engine, it might be worth reading into what it would take to buy the replacement seal and to install it.

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.

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.

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.

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.