2 qts every 3k is a lot of oil, does it leave spots or smoke? I mean wheres the oil going, there should be some signs of that. I cant see how the AFM would cause it to use more oil, even if the cyinders are shut down they shouldnt be leaking oil past the rings or valves. From my understanding the shutdown cylinders are still open via the valves and pushing air through the cylinders but they dont have fuel or fire to complete a combustion cycle, they arent necessarily building compression but then again compression isnt what causes the oil to be wiped off the cylinder walls, thats what the rings do. I think I'd have to push this issue with GM a little further something doesnt sound right.