I'm sure I don't have a leak.

I called Mercedes dealer and spoke with service person and asked for acceptable oil consumption for 1992 300TE. He said 1 liter per 1000 kilometer. I asked if he was kidding and said yes that is what Mercedes claim is acceptable. Personally I think that's ridiclous, but that what he said.

I also taked to my friend that owns an independent MB shop and he said that with that consumption I would not have fouled spark plugs; he was not suprised that the plugs looked fine.

For now I'm not going to worry about it. Maybe the next time I change the oil I do valve stem seals.