A few weeks back i noticed that my coolant reservoir had what looked like oil in it the classic sort of light milky color. after some testing i boiled it down to what i thought was a head gasket issue. i went ahead and decided to change the head gasket and glad i did cause i fixed a number of smaller issues along the way. After i finished i flushed the radiator and refilled the fluids. after driving it now for about another week i noticed i still had the two coolant and oil mixing. i have heard possibly oil cooler, or radiator?? Any advice would help

 

Radiator has the transmission cooler.

Definitely check the oil cooler. My 2005 T5 has two coolant lines running in/out of the oil cooler.