Lucas Engine Oil Stop Leak Contains No Harmful Solvents. Designed To Stop Leaks In Engines, Transmissions And Differentials. It Is Compatible With Petroleum, Semi-Synthetic And Full Synthetic Motors Oils. Renewing Your Worn Seals With No Risk Of Damage Or Eventual Corrosion. It is also an exceptional additive for worn and older engines, reducing engine noise and oil comsumption while raising oil pressure and can actually extend engine oil life by 50% or more.