Temp spike, and quick RPM reduction (06 Aveo)

[avguy]

You didn't say if this went from normal to overheating gradually or all at once. And I'm assuming that you would have mentioned if it was running bad with visible white smoke. So it sounds like the t-stat could be the culprit. But regardless of what it is, you need to get it fixed asap because these engines often blow head gaskets and/or warp heads on big overheats.
On the oil, do youself a favor and read some information about current oil technology. You can find lots of stuff on this and they all say the same thing. 5K mile OCI is consertative these days - many auto makers are using 7.5K. It took me a while to come around to this - something about an old dog being slow to learn a new trick

[BBruins12]

You didn't say if this went from normal to overheating gradually or all at once. And I'm assuming that you would have mentioned if it was running bad with visible white smoke.

Yeah, no white smoke, and it's running almost like a dream....sort of haha.

Nah, she's running fine, it happens after 8 to 12 minutes of driving, and it seems to only be happening when my AC is on...

Like I said, I'm going to pop the thermostat and replace it, run water throught the coolant system for a bit to clean it out, then put some different coolant in it.

I'll check out the new oil standards as well. I was using Quaker State Torque, as it was the least expensive Full Syn oil that was GM409 cert., but I picked up some Casteroil Edge and a FRAM Gold filter... so I'll check that out.

I was considering the Transmission fluid trick, but don't want to do that, then forget that I put it in, and not change my oil quickly enough...annnnd I've gone of topic,


Edit:
Reservoir cap started steaming, and bubbling happened... yup... thermostat.

Edit to the Edit:
Replaced the thermostat... WRECKED the metal housing which refused to come off... but that was the issue. It's only 9 months old, so that'll be sent back.