First off, Is ive seen too many oil consumption test done WRONG.!!
1st = Change oil.
2nd = Fill with Good Aftermarket 5 W 30,,(mobile ??) - As gm fluids stink !!!! - Dont use Dealers Oil. ! - Even if they say it's mobile oil..
3rd = If test still show high consumption. A non Synthetic could be run for 1,200 to 1,500 miles. then check level.. Then do a drain and refill with syn.. And test again, to see if better..
Or save time and drain and fill, and use NON synthetic. Drive 1200 - 1500 miles. Check again. - Then Drain and fill with syn. Now do the consumption test again..
BUT if you have 3,000 miles or more on engine . This may not work..
I did it,, and it did the trick.. or i got lucky..
And if i remember right,, G.M. Says that, a quart or more in 1000 miles,, then it is a warr issue..
DAMM these mass produced engines.. No more quality control..
And here is a BIG ONE..- That most owners over look..
If G.M. Authorized the P.C.V. and Valve Cover. for dealer to change,, -- Then they Acknowledged,, that there is a issue with your engine..
And now they have too fix-- ..So fight it..!. Again they just dont change parts too SEE if it does the trick. - They just confirmed it, has a issue by authorizing them too change tho"s parts..