Further to the good info from Bunny about using a M14 replacement sump plug if the threads strip. I was told about a possibly better solution recently by another M3W owner, as used on the vintage Morgan 3 Wheelers that suffer with the same problem. Use a M14 adaptor with a M10 mag plug fitted, that way you are not disturbing the "delicate" alloy case threads when the plug is removed. Plenty of adaptors and mag plugs on eBay. If your engine tends to let the oil drain into the sump easily, then sump plug removal can be frequent. The only downside is that this set up will protrude more than a plug on its own and be a bit more vulnerable. It's a chance to do some useful wire locking as well 😊.

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