Is it a solid film of oil across the top of the coolant tank?

Does it look like chocolate milk in the coolant tank? that is the real test for blown gaskets and action?

Are you saying that if you clean the coolant overflow it takes 1K to 2k miles for the 1/8 inch film to reappear?


I used to get a couple of drops of oil like scum in my C230, need to check if it is still there, MB dealer techs have told me it was normal occurance for my 95K mile engine.
Some techs I talked to who worked on asian peformance cars have said they see the same kind of scuz on those cars, and it is usual and not a sign of engine overhaul.