there is a slow but steady leak down the manifold side of my 300sd's 617. It is visable from the top of the head and down, however the valve cover gasket is clean with no leak, I have a small amount of oil in my exhaust, nothing very visible. I am hoping this is not a head gasket leak, no oil in coolant or vise versa, could my turbo oil lines be leaking? No significant oil loss, this leak is very very slow..

Advice?

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'79 240D
'79 300SD

those that are missed:
'80 300TD bandit
'76 300D cleta jill