Below are just SOME examples of how many people this is effecting, and the price in order to "possibly" fix the issue.

#10-06-01-008G:
Engine Oil Consumption on Aluminum
Block/Iron Block Engines with Active Fuel Management (AFM) (Install AFM Oil Deflector and Clean Carbon from Cylinder and/or Install Updated Valve Cover)

http://www.silveradosierra.com/vortec-5-3l-v8/tsb-10-06-01-008g-engine-oil-consumption-jan-2013-t70745.html

http://partsblog.olathetoyota.com/4920/gmc-chevy-afm-oil-consumption/

http://www.carcomplaints.com/Chevrolet/Silverado/2008/engine/excessive_oil_consumption.shtml

http://www.chevytalk.org/fusionbb/showtopic.php?tid/283310/

http://www.gm-trucks.com/forums/topic/114835-oil-consumption-issue-with-dealer/

http://answers.edmunds.com/question-Dealer-refuses-fix-5-3-LH6-GMC-Sierra-excessive-oil-consumption-don-3-years-Suggestions-159242.aspx