It contains no harmful solvents and can actually extend engine oil life by 50% or more. Leaking engines are usually older engines. Lucas Engine Oil Stop Leak is not only a leak stopper but also an excellent additive for worn engines.

If the leak is mild to moderate, we've had customers run 10,000-50,000 miles with no further issues. If the leak is more severe, or on the edge of becoming severe, the repair might last a shorter duration. The advice we always give is to act at the first sign/symptom of a cooling system problem.

Best Oil Stop Leak

1. ATP AT-205 Oil Stop Leak. ATP has come up with a solution to stop leaks and condition the rubber gaskets/ seals.
2. Liqui Moly 300 ml Oil Stop Leak.
3. BlueDevil Oil Stop Leak.
4. STP Oil Stop Leak.
5. Bar's Leaks Oil Stop Leak.
6. NO LEAK Oil Stop Leak.
7. Lucas Oil Stop Leak.
8. XADO Oil Stop Leak.

Be aware that many oil additives only provide a quick, temporary fix for small leaks. One-off emergency use will not necessarily do your engine any harm, but repeated use can do more harm than good. After a while excess additives often settle and clog up the system.

In the end, off-brand products could possibly damage your engine – we hear stories about it on a weekly basis. When you carefully follow the instructions for our engine, radiator or other stop leak products, there is no risk of damage.

It's definitely possible. The oil galleys in an engine are small, and stopping a “leak” may stop the entire flow of oil. I'm not much of a fan of mechanics in a bottle, but hey if you've got the money to replace your car/engine, there isn't much risk. It's probably better to just check and add oil as needed though.

Allow up to 200 miles/300 km for Engine Oil Stop Leak to be fully effective. If no improvement occurs, a mechanical deficiency is likely. Application does not influence oil change periods.

DIRECTIONS. Add entire bottle of stop leak to engine oil at or between oil changes. Leaks usually stop in 200 miles or 3 days of driving. If leak continues, a second application may be required or mechanical attention is needed.

How long does it take to start working? Bar's Leaks Engine Oil Stop Leak starts working the minute you install and start driving the vehicle. You will usually see results in about 200 miles or three (3) days of driving.

In the end, off-brand products could possibly damage your engine – we hear stories about it on a weekly basis. When you carefully follow the instructions for our engine, radiator or other stop leak products, there is no risk of damage.

I won't call them snake oil, because the product actually does work, but the caveat here is that it needs to be used very precisely. Use too little, and it doesn't work. Use too much, and you can get clogs in other parts of the engine cooling system.

A good radiator sealant–also called a stop-leak–can seal all kinds of cooling system leaks. It can fix the leaks inside a radiator by sealing the pores. When used correctly, a radiator stop-leak can effectively seal mild leaks in a car.