The newer engines, having tighter tolerances, require thinner oils. It has to do with the newer, more precise manufacturing technologies, and the fact that thinner oils help better fuel economy. My Bimmer, for example, require 0w-20. I don't know if your truck requires it or not, but I would definitely use synthetic oil!!
A forum community dedicated to all General Motors truck owners and enthusiasts. Come join the discussion about performance, lift kits, wheels, tires, modifications, troubleshooting, maintenance, and more!