This valve cover gasket seals the joint between the valve cover and the cylinder head on the host engine. It prevents oil leakage from the valvetrain area and keeps contaminants out of the lubricating oil. The gasket is made from cork, a material that compresses under bolt torque to conform to minor surface irregularities on the mating faces. A leaking gasket produces visible oil seepage along the cover edge and can lead to low oil levels if left unaddressed. On reinstallation, clean both sealing surfaces and tighten the cover bolts in the sequence and to the torque specified for the engine.