The Weistec Engineering Billet Oil Filter Cap for the M156 and M159 engines is designed as a direct replacement for the plastic OEM cap. ?The Billet Oil Filter Cap is installed in the exact same manner as the OEM cap, using the same O-Ring that comes supplied with new oil filters. ?The cap features lower profile threads which aids in oil filter changes on M156 and M159 engines that have a Weistec Supercharger System installed. ?