using too much coolant-no leaks-head gasket or thermostat issue?

[avguy]

If your Aveo is an AT, it might be transmission fluid and coolant mixing in the radiator. Search will find multiple reports of this happening to other '09 Aveo owners. But if it's not that, then a leak down test would tell you if the head gasket is bad.

[gettinstackz]

If your Aveo is an AT, it might be transmission fluid and coolant mixing in the radiator. Search will find multiple reports of this happening to other '09 Aveo owners. But if it's not that, then a leak down test would tell you if the head gasket is bad.

Today I disconnected the radiator hose from the thermostat & drained the antifreeze out. It wasnt too discolored - looked more brown inside the small tank. But I think everyone here is right about a head gasket issue developing, any insight into how long it might last before it brakes? what happens when it does give out? will putting a new thermostat in help the head gasket issue? how difficult is a leak down test & apprx time?

Also, I went to local autozone to buy new thermostat they looked it up and found two options for me. One with a picture for $30 and one without a picture for $90 which was out of stock. I bought the $30 because only one in stock, cheaper and they seemed certain it was the right one; It was not, the piece I bought was shaped in an "L" shape or right angle, also was 3 pieces - 2 housing pieces & the thermostat. When I pulled the thermostat out today, it was one piece with electrical connector on top but definately one bigger type deal. I have pictures of it & could upload from email. Could anyone link me to the correct thermostat part??

[FlaAveo5]

Did you ever find out the problem? That 'brown snot like stuff' was in my car, it was the coolant! That DexCool crap, turns to that brown junk, and clogs everything up! Get it out of your car!!
I had to get my engine/coolant system flushed out 4 times, to get it all out of my car,and replaced it with Peak Global lifetime Coolant. Luckily it was just starting, so I didnt have any problems, i had heard that Dex Cool was known as 'Dex Kill', because it turns into this brown crap and clogs things up, and ruins the system. Was this your solution, or did something else fix it? All I know is my 2006 Aveo Automatic, with very low miles, around 15K at the time, had this crap in it already, and if you go onto YouTube, you can see videos of this brown junk in many Chevy cars/trucks. I'd like to know if it was your problem as well, or what was the problem???