I too have encountered drain plugs tightened by, I'm pretty sure, that same gorilla. It has a way of getting around and surviving in diverse habitats. I once had a drain plug on my BMW tranny tightened a wee bit too tight. I eventually got pissed and used a huge easy out - needs a pilot hole of about 3/8 IIRC - and jammed that thing in there. This after heating the hell out of the case after the oil had drained.

Pulled it out all right.

That had a recessed female allen hole to drill into, with a crankcase plug would need a good centered hole. I use a tiny carbide ball bit on my Dremel to make a nice little starter hole right where I want it on steel, then use a 1/16 bit to make it official. This on broken steel screws I'm trying to get out so a larger bit would be good for your application, 3/32 or 1/8 perhaps. If you get a big enough easy out, and a centered hole, you can drill out enough steel so that the remaining plug is thin enough so that tapping on the edges with a small punch could break it loose.

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1986 300SDL, 362K
1984 300D, 138K