I wanted to keep the gunk out of my intake manifold as it has a habit of plugging up the ALDA and boost pressure sensor hose. When I took the air intake duct off leading to the intake manifold it had about a 1/4" of black gooey goop covering it and the intake manifold. I bought the car 3 years ago with 135k on it. It now has 175K. I heard that keeping the oil level at about 1/2 way between the fill mark and low mark minimizes oil vapor entering the intake manifold, which I understand is a major contributor to the goop buildup. Perhaps most of the goop was there from the prior owner who kept it full.
I know what you are saying about leaving well enough alone. It's probably the best advise.

Thanks

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Walter
1992 300D 175K