Oil in Antifreeze?

[Fishhawk]

Here's my probelm. Saturday I dumped the antifreeze in my 85 GT, 5-spd and refilled it with water. My local drag strip requires no antifreeze to test and tune. Sunday I make 6 passes and call it a day. I get home I drain the water and refill the radiator with the antifreeze that I previously had drained. (The pan was cleaned before the antifreeze was drained into it). The motor was cold when I refilled the radiator. I start the motor to warm it up so the thermostat will open. When the motor warmed up I noticed what seemed like oil floating in the antifreeze. Could this be anything other then a blown head gasket? Could this be anything other then oil? Does oil float on top of antifreeze or does it foam? The car runs fine. Oil preassure is 55 psi.,(normal) and the water temp is steady at 185 degrees (also normal). Any opinions are welcome.

 

[criticman]

Have you ever cleaned your cooling system?

I know before I installed new radiator, water pump, hoses, thermostat, etc...the antifreeze looked pretty nasty no matter how fresh it was.

Also, are you the original owner? Could someone have put stopleak in the cooling system (generally makes things black-ish when system heats up and flows)?

 

[Fishhawk]

I am the original owner. I replaced the radiator in the late 90's. I had it flushed in May and have done all the engine mods since then. The radiator has been dumped and refilled about 5 times this summer.