There is a fair amount of oil that takes a long time to drain out. I recently had my 240D on an engine stand for three weeks with oil pan off, and it never did completely stop dripping oil. It probably seemed like a lot more than it really was, but I had to keep cleaning up the mess underneath. It gave me understanding of why the oil doesn't look that clean after an oil change. And after putting new oil back in after the outage and 3 weeks of draining, it still didn't look clean.

So...I am going to put nothing but oil in there, because anything you put in may never come back out.

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1976 240D
1987 560SL
2007 E320 Bluetec
1998 C280 (now son’s car)
1982 240D Manual - Sold