If it happened suddenly and its too thick for coolant to flow its oil the earlier single cam S model saturns especially the heads cracked where the cam rides allowing oil enter the cooling system.Once in a while not too often it allows coolant into the oil you would have to replace the head water pump thermostat all coolant hoses heater hoses etc.You also have to start by back flushing the heater core all by itself then flushing the whole cooling system i found a petroleum based coolant flush worked best.We used a product called Eskimo at the saturn dealership sometimes when you remove the valve cover you can see a clean spot in the oil residue where the coolant has cleaned th oil away.

Answered by saturntech9 (expert)
23,200 answers provided

So as of right now, I have to replace all that you mentioned in your response? "Back Flushing" would I find that in the repair manuals they sell at the auto parts store? I've worked on my cars before, nothing major, but I have replaced a water pump on another 96 Saturn I had owned. So I'm asking, because if I can "back flush" the heater core myself, then that's what I'll do.
I want to thank you for taking the time to answer my question, I know you get a lot everyday. But I really need my car for work, since I'm the only one with income at the moment.

Response from cynthiacruz
1 question asked

You will have to also replace the coolant bottle plus all the other things i mentioned.As far as back flushing the heater core you would take a garden hose with both heater hoses off and spray into the one nipple of the heater core to push out the oil/coolant out of the other heater core nipple.Also do that with the radiator it will be easier to flush the heater core with the head off.Another trick i use is drill a 1/4"hole in the center of the coolant cap and open the radiator drain and used compressed air to pressurize the cooling system threw the cap turn the compressor regulator way down and with water and air use that to push the oil out.With that many miles if your going to keep the car i would just find a engine with a lot less miles then yours.Instead of getting a head for that car.

Answered by saturntech9 (expert)
23,200 answers provided

Thank you so much! And yes, I did consider just getting a whole other engine for it because I do a lot of traveling for work. Thanks again, you time and answers have helped me.

Response from cynthiacruz
1 question asked

You can use a 1995-1998 single cam saturn engine doesn't matter which model.That should help you find a engine.

Answered by saturntech9 (expert)
23,200 answers provided