Opened my oil filler and there was a lot of creamy oil/water goo around the inside of the filler neck. I am NOT noticing any oil in the coolant NOR any other obvious signs of coolant in the oil (nothing on the dipstick). Just around the filler. So my mind travels to condensation or gasket leakage. Is this a viable scenario? I oiled up the gasket mating surface and it looks like there may be about 45 degrees of the gasket that may not be sealing. There wasere about 2 tablespoons of goo that I cleaned out. It has been about a month since I last had the cap off.

As an aside, I am only seeing gaskets for pre '93 vehicles. Do I need to buy a whole new cap for my '99 E320?

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1999 E320 (gave to daughter) 250K
1994 F150 (may be the end of its road) 240K
1989 560 SL (Reassembly after paint job) 160K
1986 560 SL (deceased., gave it's life protecting my wife)
1988 300 TE (departed)
1994 945T (still running strong with an upgraded cam) 349K
1986 242Ti (deceased)
1968 GT500KR (under restoration)