Bar’s LeaksProfessional Main Seal Motor Oil Leak Repair, No. MS-1, is a high-tech synthetic blend of additives to provide a cost-effective chemical repair for engine oil leaks originating in the rear or front main seal, as well as camshaft, crankshaft and timing cover seals. It’s guaranteed by the company to stop any oil leak in a single dose. The product works in two ways: three specially engineered seal-rejuvenating additives restore seal size, flexibility and elasticity, while an advanced seal polymer package builds a polymetric film around the seal to help prevent excess oil bypassing the seal during normal engine operation.