I'll second or third the above mentioned oil leaks.

M103 and M104 engines are known for oil leaks at the right rear corner (passenger side) of the head gasket and at the front timing chain cover seal.

Most leaks appear as just a dampness with an oil film, but eventually over time will get slowly worse.

It's just an oil leak, and you can generally let them leak until they are leaking so bad that you can't stand it anymore.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".