'95 E320 Oil filler cap leaking

[TheEngineer]

There was always a little oil around the oil filler cap and I just wiped it off. Last week I swapped it for a filler cap from a BMW I had laying around. The fuel filler caps are the same. I put the cap from the E320 on the fuel tank of my 280SL. It leaked fuel big time. The BMW cap is tight. It looks like the E320 cap bottoms out on the plastic rim, so the rubber seal doesn't compress. It is the original cap that came with the car.
This is not a question, but an observation.

[deanyel]

This is a bit confusing, and seems to lack an actual question.

[Parrot of Doom]

I recently changed the gasket on my cap. No more leaks.