Ok, I am new to this site but as a GM tech who has been pushed too far, its time the truth came out! I know for a fact in the northeast, there is a service bulletin #PI056E: and its titled wax coating on frame peeling, metal shows corrosion/ rusting. this covers 2011-2015 GM full frame vehicles.
2011-2015 cadillac Escalade models
2011-2014 Chevy Avalanche
2011-2015 chevy Express, Silverado, Suburban, Tahoe
2011-2015 GMC Savana, Sierra, Yukon
What the dealerships dont want you to know is the info i have provided, if your vehicle has rust issues just head to your GM dealer of choice and tell them you see premature rusting on the frame and would like it taken care of. and im sure like any good sleazy GM dealership they will feed you a line of BS, but just tell them that bulletin number and they are required to fix the vehicle at GM's expense plus give you a GM paid rental for the duration of the repair.(which by the way takes at least 4 days)
If there are any questions feel free to contact me, knowledge is power use it or loose it!