1997 Pontiac Sunfire

Engine Cooling problem
1997 Pontiac Sunfire 4 cyl Front Wheel Drive Manual 195000 miles

Hello I have a 1997 Pontiac Sunfire, and lately its been overheating, the check engine lights comes on. And I had it checked and it says it needs an O2 Sensor. Now it overheats sometimes. I did have some problems with the coolant. Sometimes it would drain but it doesnt have any leaks. And then I put some coolant in it and that seemed to last longer but even today I was driving and it overheated the first 10 minutes I drove it and then after a little while it went back down to normal temperature what could this be? Possibly? Would the O2 Sensor be related?
April 17, 2009.

Try replacing the thermostat don't work come on back and we'll get into it deeper.

Apr 18, 2009.