Bought a used 2006 gp-gxp in Jan 2010. Received a GM Certified Warranty-12mo-12thousand miles. Almost immediately i noticed excessive oil consumption. Also bought an extended service warranty from the dealer thru CNA extended warranty. Took the vehicle back to the dealer numerous times in 2010 complaining about the oil usage. Was told the 5.3L engines uses up to a quart of oil every 2000 miles. My car was using 3-4 qts at 2000 miles. The dealership told me keep track of the usage and not to worry because i have an extended warranty. Finally after months of complaining they agreed to an oil consumption test. By this time the GM 12mo-12000 warranty was up. After the dealership doing the test thru 4 oil changes they discovered it was using better than 4 qts between oil changes and they contacted CNA. CNA denied my claim because GM has a service bulleting on the problem. They know the 5.3L v-8 has a manufacturers defect in the displacement on demand system causing them to use oil. Apparently CNA does not cover manufacturers defect when there is a service bulletin explaining the problem and the fix. They say since no part failed they are not responsible and of course GM says its my problem. I have owned nothing but GM's since i started driving 44 years ago. I will never, I repeat never buy another American built vehicle as long as i live. I counted up I have had 7 new GM's and 15 used ones. Please if you don't take anything else away from this, do not buy an extended warranty from CNA Auto extended warranty or Dave Sinclair GMC in St Louis, Missouri. You have no idea how hard it is to make these statements being i built my first car, a 57 chevy 2 dr hdtp from a car bought at a junkyard.