Well, it's hard to say if it's oil or PS fluid when it's all filthy. But the ofhg wouldn't leak to the top.
It could also be the vanos oil line I suppose...you try tightening that? Also, make sure the inside of the oil filter is clean...and also, I don't think this matters, but make sure it has it's o-rings at the bottom of the filter cap.
OFHG is a simple repair...and a $10 part. For $1300, I'd drive to Dayton, do it, take you to dinner, and drive back!
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Mangofy your E46!