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

2009 chevy aveo lt 1.6 4 door. About 6 months ago had both upper/lower radiator hoses develop leaks mid-pipe at different times - fixed both, no leaks anymore. For about the past 2 months ever since my check engine light has came on (determined to be the thermostat) has been going through more than ordinary amount of coolant - every time I check its about halfway . Also have noticed snot-like build up inside the coolant rim as well as light brown colored fluid (coolant I used was florescent green) and possibly little oil blotches on fluid surface maybe? have seen some stuff on here about coolant & oil mixing? connection to a head gasket issue (no excessive smoke)? could i be using extra coolant due to thermostat that needs to be replaced? need help! eager to understand!

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.

A quick test to see if antifreeze is present in the oil is to take the oil fill cap off and taste the condensate on the bottom. If it is sweet, you have antifreeze in the oil and as you have noted already oil in the antifreeze - indicators of a bad head gasket. If the condensate is not sweet follow avguy's advice and perform a leak down test.

If your coolant is turning brown and getting a snot like consistency, you have a bad head gasket. It may not be a full blown head gasket, but oil and coolant are definitely mixing.

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Originally Posted by 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.

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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??

Did you get just a thermostat or a thermostat with a metal housing?

The stat you bought is for the first gen Aveo, so you need to return it and get the one with the sensor.

The leak down test isn't difficult to do, but you'll need to buy the tester, unless you can find someone renting or loaning one. OTOH, if you're not planning on a DIY repair, perhaps it might make more sense to have a shop do the test, followed by the repair. Fluids mixing is never a good thing, so you should get this fixed asap.

2x on avguy's comments. Coolant in the oil can lead to buildup on cylinder walls, eventually rings or worse will break !
Broke a crankshaft once due to exactly this issue.

Chuck

Antifreeze in the oil can wash out rod and main bearings. I have an RCMP Crown Vic in the shop with a rod knocking due to this right now.

If the leak down test comes back ok, I'd suggest you consider the radiatior/transmission cooler issue that I posted in my first reply.
This is a systemic issue in the '09 and here below is another, brand new instance that was just posted. (post #3)

http://www.aveoforum.com/forum/f85/s...my-09-a-20733/

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???