bytal

So we recently found oil in the coolant reservoir of our 06 C230. I'm trying to figure out whether its engine oil or ATF and how it got there. I dumped the engine oil and asides from being dirty, it looked like engine oil, I pulled one of the transmission lines off the cooler to check the transmission fluid for contamination. No milkshake there either. I've tried revving the engine up good to check for white smoke to see if there is a head gasket leak and that has come up negative too. I know there could still potentially be a leak between an oil galley and a coolant galley in the head. Are the oil coolers on these cars cooled with coolant? I didn't see any lines running to the cooler, but I'm wondering if the coolant is run directly through the oil filter housing. I know radiator is quite possible too, and heard that there were problems with the Valeos, but I believe that was earlier that 2006. TIA

MBENZTECH

Replace engine oil filter housing/cooler assembly. It is one of the most common problems for M272/M273 engines.

insame1

Are you loosing any fluid. how bad is coolant reservoir?

C230 Sport Coup

Send the fluid to Blackstone labs for analysis.

Peehussle

Oil cooler gasket needs to be replaced