I have a 2008 lt2 with 30,000 miles that seems to use coolant.
I took it to the dealer for an oil change and mentioned a gurgling noise when I accelerate. they added coolant and told me that the newer coolants evaporate(?). 2,000 miles after they filled it its doing the same thing.
Can coolant really evaporate?

 

Since the coolant system is sealed, the only way for it to evaporate would be a breach in the sealed system and that's called a coolant leak. Find a new dealer.

 

The oil level seems to be high (over the full mark), is it possible to be leaking internally?

 

It's very possible. Probably the head gasket is bad. Does the oil have a milky color?

 

My overflow jug has a vented cap. (a tiny hole in the middle of it).

That is not sealed.. But yes the system is..

 

Then there you have it, the coolant evaporates through the pressure cap.

 

I have no issue with mine, just saying the overflow cap is vented. Not the pressure cap.

Didn't mean for my statement to upset anyone..

 

Just heard back from the dealer. They are tearing down the engine to find the leak.

 

Since April they replaced the head gaskets. The same problem is still there so now they are replacing the engine.

 

I had this same problem at about the same mileage. FWIW the dealer told me the two halves of the block were improperly fused together and the seam had failed, allowing coolant to leak out and bubbles to enter the system.

I'm happy to hear they're doing right by you and replacing the motor.