As a car ages, engine seals harden and shrink from the plasticizers being removed over time. This means leaks, and nobody has time for that. This professional strength synthetic stop leak revitalizes these worn seals and gaskets to restore them to like-new performance. This is Bar's Leaks strongest formula ever to stop main seal, valve seals, timing cover seal, cam seals, crankshaft seal, oil pan, valve cover and all other oil leaks.