Hello,

I did an oil change on my 2002 Mini Cooper (non-S), which has an old-style oil filter housing. It's Europe-spec if it matters.
I did put the spring and cage back in the housing as explained here: https://www.minimania.com/MINI__02_0...roblem___Hints

After finishing up, I noticed a plastic part covered in old oil on the ground:


What is that part?

• my first suspicion was an oil filter housing internal part. It's not from the cap, but maybe from the base? It's hard to find a diagram of the discontinued old-style housing, but I can't match it to anything on photos I found (especially it doesn't look like a drain plunger).
• maybe it's something from near the housing that became loose and unscrewed when I was removing the housing cap? If that's the case, where does it go? I could just screw it back in.
• maybe it's something that was left in the engine bay by a previous owner/mechanic and was dislodged when removing the housing cap?

My family mechanic (not very knowledgeable about Minis) isn't too sure either. His best guess is some sort of breather in the air input, but he's not affirmative.

I did a 15 min drive test and it seems to drive just fine, I did not notice any leak.

Thanks!

 

Update: after spending way too much time trying to find where this thing could go near the place it fell off and scouring diagrams to find where it could, I used Google Lens to try to see similar parts.
The form and lack of any seemingly useful feature suggest that it might just be a liquid fill adapter or something like that that was left by a previous owner/mechanic and was dislodged by the oil pouring out of the oil filter housing.

Unless someone remember that part going somewhere, I'm going to work on that assumption for the time being.