Anybody else having problems losing/consuming oil? I have an 07' CTS with 85,000 miles and it wouldn't start this morning, turns out it was only because it was 2.5 quarts low on oil. WHAT?! Check engine light never came on or anything and never noticed any spots in the driveway. Took it to a local shop with a GREAT reputation and they said they couldn't find a leak anywhere. Not sure where to go from here.
I have the same year CTS and the 3.6 is known for eating oil. I use Mobil 1 full synthetic and it helps.