Head Gasket Blown?

I have a 99 Saturn sl2 DOHC. The car has been losing oil, it isn't leaking anywhere and doesn't appear to be burning. I have to keep adding a quart about every 2-3 weeks. I just recently did an oil change, just oil. No coolant mixed in. I believe that it may have something to do with my head gasket or even with the engine block(I don't know that much about cars as you can tell) as the car has overheated once for about 3 1/2 minutes before I shut it off and let it sit overnight before I tried starting it again. The car isn't getting any heat. I need to replace the thermostat. Anyone have any ideas on what could be going wrong? I would like to trade it in and get rid of it but I cannot afford a monthly payment right now. Thanks for your help.

Doubtful its a head gasket, or when you pop the hood you would see oil all over the block.

Since you haven't pinpointed any obvious leaks, I'm going to assume your are burning oil.

First, I'd see if the car logged any codes. Head over to an autozone or equivalent store. Most do free OBD2 scans for cars, and would be able to tell you if your ECU logged anything.

Then you get to run through a list, preferably while the vehicle is running since that's when there will be oil pressure. You will need ramps or a pit to do this, so start scouting craigslist for cheap ramps.
Check the Oil filter, make sure its secured properly and sealed.
Check the oil pan, feel the gasket. It might not be an obvious leak if its only leaking off the oil pan. Feel the gasket around the entire pan and make sure its sealed. If you park on hills, the oil might only be leaking out when the car is at an inclination. Odd but it happens.

If not, remove the spark plugs, see if there is oil leaking into the combustion chambers. If its an internal leak, your options are limited. You might as well start calling around junk yards and asking for an engine, since that will be cheaper than having yours repaired. The AAA shop back home does a plug and play swap for only $200 hundred bucks on most domestics. Just source the engine.

Good luck, obviously if you can get a mechanic to diagnose it, you will have the problem solved.

Ya I know an "off the books" mechanic, he just does it as a side job, I help him out with computer shit and he helps me out with my car. He has done the scan and he didn't find anything but that was back in the winter. Thanks for the tips, Ill check it out when I can and get back. If anyone else has any tips, of course go ahead and reply. Thanks!

Seeing as you have not done the thermostat, I'm going to guess that you are still rocking most of the original coolant. Now coolant may not have anything to do with the oil going missing, but it may be a contributing factor.

You haven't mentioned the milage, but I know Dexcool only has a 10 year life, acording to GM.

97K miles. They housing for the thermostat was broken so that was replaced in December janurary 08-09. Not the entire thermostat. The coolant was replaced then.