Hello all, ive recently bought a new to me single owner 2014 gmc sierra 4.3 4x4 double cab with 43,000 miles on it. It has flex fuel standard and was wondering wether or not i should run e85. It is available local and pretty cheap, but ive heard that if the truck has ran gas most of its life the e85 would cleanse the deposits and possibly clog the fuel lines or fuel pump. Should it be safe to switch over to e85 ? Or could i just start running 89 since ive also read that its more beneficial running 89 or 93 over 87 due to detonation