This valve cover gasket seals the joint between the valve cover and the cylinder head on the host engine. It prevents oil from escaping the valvetrain area, maintaining proper lubrication pressure to the rocker arms and valve stems. A failed gasket allows oil to leak externally, which can lead to low oil levels and contamination of the engine exterior. The gasket is manufactured to match the original sealing profile, ensuring it compresses evenly against the cover flange and the head surface. On reinstallation, clean both mating surfaces thoroughly and tighten the cover bolts in the sequence and to the torque specified for the engine.