Owned the car a couple months, no troubles.. Turned the heat on this morning to burn off windsheild dew.. Now car overheats and I got milkshake oil... What could have happened? Was something hidden from me wheras I never tested heat when I purchased.. Its Florida car, so always use AC.. Any ideas? Thx

 

No, of course it has noting to do with using the heat in the car.

The most likely cause is one or more of the following:
- head gasket
- cracked head
- cracked block

Your "milkshake oil" statement I am guessing means you see something other than oil in the oil - which would be water and antifreeze.

You need to take it to a mechanic to run some tests to determine where the problem lay, and to determine if it is worthwhile to fix.

 

Milkshake oil tells you the reality of it, blown head gasket or water pump. I'd replace both pronto, that oil and coolant will destroy the crankshaft and camshafts . Do not drive , start it or anything else!
Remove the head have it inspected for cracks, whilst you have the front cover off to get at the timing chain, replace the water pump, balance shaft gear chain, and the timing chain.
It's a tedious job but not impossible.
I've always used FelPro gaskets but that's just me, I tend to keep a car forever or until somebody needs to unload their cash into my hands!

It's an 11, so worth the repairs

Here's a how to check video

 

Well, you've been losing coolant for months, and letting it run hot. And since you couldn't get the crank bolt off, you're not going to be able to fix this on your own.

X2 to what whopper said, get it to a shop.

X2 to what oldbue said, Do not drive, start it or anything else!

 

They probably used bar alum fix head seal or something.. They ripped me OFF... I kept checking recovery tank for coolant loss and had zero loss at masking tape line mark.. However when I take rad cap off I show a loss there? How and why there but not recovery tank? This sux, I was hoping for a good car whereas I am just lowly factory worker with only $78 in savings acct..

God grant me the serenity to accept the things I cannot change and the courage to change the things I can and the wisdom to know the diff

 

These things happen, a head gasket and your back on your way.

Chevrolet Cobalt Head Gasket - Engine Gaskets - Felpro VR Gaskets DNJ Rock Genuine - 2007 2006 2005 2008 2010 2009 07 06 05 08 10 09 - PartsGeek.com

 

I'm wondering if this might have been the root of the problem. If the pressure cap were bad, the engine could push coolant out into the recovery tank, but couldn't properly pull it back into the engine, because the suction was broken by the bad cap. This would allow air to get pulled in, displacing coolant, and causing an overheat condition.

 

The issue was masked when I purchased the car.. I kept an eye on my coolant recover tank and wasnt seeing any coolant loss.. The issue came to ahead when car started to overheat the other day and recover tank was normal. Checked under cap - zero coolant.. I suspect my thump thump thump noise I hear is an on the fritz crank bearing because of antifreeze intrusion that happen before me.. At this point, I will just keep topping it off with water and drive it.. Car runs great.. Ill keep my eyes open for a new engine and do a change..
Drive until it wont drive, then act