Mini oil pressure relief valve cup
12H865- OIL PRESSURE RELIEF VALVE CUP
The cap that sits on the end of the oil pressure release spring which should be lightly ground in to get proper seating. Cooper S engines had the shorter stronger spring AEA536 and the rest had 6K853 but most fit the AEA536. The alternative to this cap is a ball bearing BLS916. The washer that goes between the cap and block when undoing this is 6K431.