Hapco Main Sta sealer is a unique, 100% pure blend of natural and synthetic lubricants. Effectively stops and prevents engine oil leaks by revitalizing all rubber seals and gaskets. Compatible with all conventional and synthetic oils. Main Sta is also recommended as a superior break-in additive for new or rebuilt motors. Makes new engines LEAKPROOF by lubricating vital areas to help prevent wear and shrinkage. Does not contain petroleum distillates, which can harm or destroy seals. For Best Results: Add one 16 oz. bottle of Main Sta directly to engine oil. Drive vehicle as normal to allow circulation of fluids. No need to change oil immediately after leak is repaired, Main Sta will dissipate on its own. Safe for all gasoline, diesel and marine engines.