I recently did an oil change on my 87 NA. I only until now got around to disposing the old oil when I noticed at the bottom of the pan little specks of green...looked a lot like anti freeze. There are no other signs of a head gasket issue. Although I did have to add antifreeze in the resivor 2 times. I thought nothing of it cuz I recently changed the rad. I checked the resivor and no traces of oil in it as well the oil is not foaming up. Anyone have and ideas??