adding coolant

just a quick question here on adding coolant. I have a 07 with 15,000 miles on it and have had to top off the coolant tank approx 3 times . each time it would be at the min mark and i top it off to the max mark. never see a leak but every great once in a while i get a whiff of coolant smell . is this common on these cars or should i have the dealer do a leak test on it and see if there is a problem. any known problems with these cars such as head gasket leaks or freeze plug leaks and so on.

You can try a cooling system pressure tester to see if there is a pinhole leak somewhere...when the engine is cold. Plus, if you can smell it in the exhaust then you might have a head gasket leak. But I find that hard to believe on such a new car. If the car is still under warranty, then have the dealer assess it for you. Hope this helps!

On my '06 LT, I had to have the freeze plugs resealed at about 35k. The dealer discovered the leaking during a routine oil change and fixed it under warrenty. I think they said it's a fairly common occurance and to just keep an eye out for it.

I have had the same problem on my 05. The exact problem. I added coolant to the reservoir 3 times. After a few miles it went down to the minimum line each time. I don't know why it did this, but I just don't add any coolant and it stays at the minimum line. I'm glad you asked. I couldn't figure it out either.

I know some 07 have a external coolant leak the thermostat bypass pipe to cylinder head near cyl4 intake port. cylinder head replacement is the fix. will be easier to see from under the vehicle; look for the hose that goes from the heater core to the cylinder head

i had an 08 that needed frequent top ups. pressure tested with no pressure drop and no external leaks. remove plugs and inspected cylinder combustion chamber; all ok. remove cyl head and inspected; all ok. reassembled with new head gasket. problem returned. talked to gm master tech and replaced cylinder head which fixed problem.