Bad Thermostat?

I have a 2002 Caviler.
Somewhat recently the car has been not staying at a constant temperature. It will rise above the middle (where it would always just stay at until recently) a notch and then go down a notch below the middle. I have never replaced the thermostat and I have had it around 8 years and the car has around 60,000 miles.
Has anyone had similar problems? Did replacing the thermostat fix them?

Is the antifreeze levels correct? Does it only do it when stooped? Does the fan come on when car is warm? Does the other fan come on when the ac is turned on?

I don’t like throwing parts at a problem by any means but it seems a new thermostat might fix your problem. If the fault remains…you will still have a new thermostat and you will be one step closer to pinpointing the exact reason for the malfunction. I’d go for it since it’s actually preventative maintenance. +1 for knfenimore as well.

There is a an antifreeze leak. It takes about a gallon a year. It’s not a gasket problem because there are actually a spot on the radiator that leaks and there is a hose that leaks at the clamp when it is really cold. But I do keep up on the level in the reservoir.

It does it all the time- stopped or driving, straight or slopped.

I was worried that the fan was not coming on but I checked last week after having the car idle for a while. It came on when the temp gauge was at the half mark, so I do think the fan is working. I guess I did not know there are two fans. I have always just seen the one but if there are two they seem to both be working well.

Time to visit an auto parts store and pick up that new thermostat. Good luck.

If you have dex-cool and a leak you should look at your coolant to make sure sludge problem is not occurring. Sludge problem seems to be associated to exposure to oxygen.

Thanks missileman.

And I do use dex-cool. I saw that dex-cool has slugging problems. How do I check for sludge? And would it be worth changing coolant to avoid sludge?

I think you do have only one fan. It’s real obvious.

Another possibility is the temperature sending unit.