This is a good used oil filler cap from a Gen 1 MINI we parted out. As you can see it will fit both the W10 and W11 engine. Comes as seen in pictures.
Fits Gen 1 MINI:
2002-2006 R50 MINI Cooper Hatchback
2002-2006 R53 MINI Cooper S Hatchback
2005-2008 R52 MINI Cooper Convertible and Cabrio S