When I bought the car, oil wasn't getting in the air filter, it's a more recent development. It's not a lot, though, sort of a mist. I don't want that oil to get into the vacuum system, I'll have an oil leak under the seats or something and I'll have to replace everything vacuum. Also it appears there is no gasket at all on the vacuum pump for some reason, or the one that's there is degraded and covered in oil. I think the oil in the air filter might the the oil separator valve failure, it's worth it to replace anyway when the oil pan is off.

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1980 240d
1999 SL500