It's a good fit yes, you get some resistance when you pull and once past it you can slide it out normally. It seems to have enough crank pressure to spit quite a bit against the cap and wet it, can see it clearly on the cap's underside. That makes me wonder if it ends up leaking from there, but the cap is twisted outwards, so the logical thing would be for it to leak the oppsoite way.

I can't think of anything else that carries oil nearby, the t u r b o aluminium duct just carries pressurized air and I can't see any oil dirt in the junctions. And my turbo isn't leaking oil AFAIK, exhaust gas is always perfectly clear even from cold start.