I did the turbo return seal (TRS) job on my 83 300sd last august. After that, I still had a slow leak at the rubber-gasket to oil-pan connection.

My observations: If I fill the oil all the way to "full" my car leaks from the rubber-gasket to oil-pan on (upward incline, downward incline, flat, any incline). If I fill the oil to one half quart below full, it does not leak.

Also, with one-half below full, If I park with my front end on an incline, the TRS leaks. If I park with the front end on a decline the TRS does not leak...most importaintly when my car is level it doesn't leak.

Anyway, my point is that oil level and vehicle incline has an impact on the TRS leakage .