This happened to my recently purchased 240D a couple winters ago. The Oil filter cover blew in my driveway while I was backing out, but I shut it down as soon as I saw the huge black puddle. Turned out one stud had already been repaired by the PO. Then the other one popped with me. Studs replaced with metric bolts inserted up through the bottom of the stripped canister stud holes. The bolt heads had to be ground on one side for fit and clearance as the canister stud holes are very close to the canister wall. I reinstalled the cover nuts and now there's no more worry of studs/helicoils pulling loose.

Happy Motoring, Mark

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DrDKW