oil in radiator overfill

why am i getting oil in my radiator overfill tank. it has never overheated , no white smoke out talepipe. i noticed that my oil drops.
it was thick light brown oil in the overfill rad. tank.

This usually happens when a head gasket blows or a cracked head. The oil pressure is greater than the coolant pressure so oil goes to the radiator/ overflo. Sorry!!

....Unless someone put oil in the radiator, lol. More than likely it is a head gasket or cracked head. It is easy to change head gaskets though. Good Luck.

is the head gasket the one after you remove the the rocker cover or is it the one below that?
thanks

it's under the head, between the head and block