First of all, under what conditions does the overheating occur? Speeds, how long does it take, etc. Do you hear the radiator fan turning on?
Milky oil is not the most common result of a leaking cylinder head gasket. Coolant getting into an oil passage won't result in overheating. It's much more common for coolant to get sucked into the combustion chamber and burned. You'll be losing coolant and you might see white smoke from the tail pipe.
There's two tests you can do to verify a leaking head gasket. If you're losing coolant very slowly, add a small bottle of dark purple dye to the coolant, then search a day later with a black light. The dye will show up as a bright yellow stain that you can follow back to the source. If you find it inside the tail pipe, suspect the head gasket.
You can also have your mechanic perform a chemical test at the radiator. With the engine running, you draw air from the radiator through a glass cylinder with two chambers partially-filled with a special dark blue liquid. If combustion gases are present, the liquid will turn bright yellow.
Monday, December 21st, 2015 AT 7:03 PM