Oil in Coolant Reservoir Causes, Effects, and Solutions

A blown head gasket allowing oil into the coolant would also allow coolant into the oil, causing a frothy or milky look. The tech said he thinks it's the DSG transmission cooler since the oil in the coolant is very dark, vs the engine oil which is as clean as a whistle. Blown head gasket\cracked head if you're not getting a CEL with a miss. Oil and coolant only combine into that nice brown goo under high ... Coolant can react to oil and make it sludge, which isn't good, and coolant in your lubrication system would be bad. So the next step is to ... This oil is from tranny as it uses the radiator as a form to cool down the tranny oil. The color of the mess was milkshake. This is quite a common problem with the 272/273 motors. Replacing the seal alone will not fix the entire problem you have at this point. You ... Only way to tell at this point is to perform a compression and leak-down test to see if it really is the head gasket or something else. Fresh ... There's evidence of oil residue in the coolant overflow tank in my 2012 Outback 3.6R. It has 150K miles, and has been dealer maintained. Usually the "O" rings in the engine oil cooler are leaking internally. Easy to repair in an afternoon. Rob. Quote. I have a 09 Beetle, my mechanic called me with my issue and it was a failed oil cooler. I had oil in the coolant and the car overheated.