When I opened the cap on my radiator their are little brown swirls in it. It appears to be oil( I just put red fliud in the radiator that is supposed to lower the tempabout two weeks ago). Can oil in the antifreeze be something other than a head gastket? Possibly turbo related? My turbo is getting a little tired at 63000 miles, and the bottom end of the motor only has 2000 miles on it. They installed a new head gasket when they installed the new short block. Also their is no antfreeze in the oil.