You have a problem...now, since you know you have a problem you should get to the bottom of it. I would suspect the head gasket since you say it was just replaced...did you follow the correct torque/sequence when you tightened the bolts? Coolant can get into the crankcase from either a crack in the block or head or a bad gasket...since you just did the gasket I would start looking there.

You don't want to run on contaminated oil or risk hydrolocking the engine if the head gasket is bad so you should find the source of the leak and fix it asap.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz