seeing that this is a mercedes engine with slightly over 100 k miles the engine is well lubed by the oil that should be on the inside. I fear that the dreaded gasket will cost me money in one of the coming months. The water looks oil free and the oil is very clean. No signs of comtamination in both. Since I loose cooling fluid without finding it on the floor it could very well be a haedgasket that is failing. But since most Benz engines will run for a long time while leaking oil and it is an expensive job I tend to postpone as long as possible. I once pressurized the cooling system and looked for traces of leaking fluid and could not find any ( I really climbed in and under the car to find something) and am therefore not in a hurry.