ok so i bought this 2003 f250 5.4 about 3 or 4 months ago.. runs great and all.. the other day i was checking up on fluid levels and noticed what seems like oil sitting on top of the antifreeze in the antifreeze tank.. there is no antifreeze in the oil, just oil in the antifreeze. truck doesnt overheat, doesnt seem to have a loss of power, and theres no white smoke.. nothing is leaking, only thing i can see is this oily substance that is seperated from the antifreeze and is on top.. im trying to figure out whether it is a bad head gasket, cracked head or what. i was told if the truck has an external oil cooler inside the radiator could cause this to happen. so what is going on with the truck and also, do i have an external oil cooler?

 

Automatic transmission? What's the fluid level like on the trans. dip stick?

 

How do you know there isn't any coolant in your oil? You can't tell by looking as oil doesn't always turn milky when exposed to fluid.

A better way is, when the engine is hot, turn it off, open the hood, remove the dipstick and touch the exhaust manifold with the tip of the dipstick, which deposits a small dab of oil on the hot manifold. It will smoke, which is expected........but of you hear a sizzle, like frying bacon, then you have coolant in the oil.

As mentioned it could also be automatic transmission fluid (in which case you may want to panic).

 

Tranny fluid is as red as can be and oil is the regular color it is. I changed it and looked at the oil. Nothing was separated. The oil would sit on top of the antifreeze.

 

if the trans and oil look good. then could have been a previous repair (IE leaking trans cooler or lower intake) and they never cleaned the reservoir after the repair.

 

Try flushing your radiator, I've seen some nasty stuff come out of old systems.