need help...please dont know what to do?

I have a 1991 Mazda B2200 with a 2.2L non-turbo engine. I found out that it was leaking oil into the radiator or mixing them somewhere else.... When you open up the radiator cap it looks kinda like a milkshake (white)....i have taken it apart and cleaned it but still have the same problem.....Can anyone help????

head gasket

hope you didnt over heat it too bad. if not a head gasket should be all you need good luck!!

Are you sure that it's not just mix of oil and condensed water on the bottom of the oil cap? That can easily happen in winter if only short drives are made,a nd the engine doesn't get hot enough to boil off any condensed water.

Do you really notice other symptoms, like overheating, oil in the radiator fluid, or big white smoke out the tailpipe? Or just the goo under the oil cap?