2000 Saturn Station Wagon

If you have oil in the coolant most likely you have a oil cooler that leaked oil into the coolant. You would have to remove the oil cooler and put air pressure into to make sure that's what it was. But all the car's I have seen like that that's what was the cause. It will overheat and the sooner you fix it the better and easier it will be to flush it. The longer you wait the more oil will get into the coolant and harder it will be to flush the oil out.