This valve cover gasket seals the joint between the cylinder head and the valve cover on the host engine. It prevents oil leaks and maintains crankcase pressure, which is necessary for proper lubrication of the valvetrain components. A degraded gasket allows oil to weep onto the exhaust manifold or the engine block exterior, creating a visible leak and a burning-oil odor. This original gasket matches the profile of the sealing groove in the valve cover, so it compresses to the correct thickness without over-torquing the fasteners. On reinstallation, clean both sealing surfaces and tighten the cover bolts in the sequence and to the torque value specified for the engine.