Now have 68000 miles on our 2012 GMC Sierra XLT 2500HD Duramax/Allison....no mechanical issues on it so far...only thing I never figured out was why some design engineer could not have come up with a better fill on the DEF tank....IMO it's ridiculous where it's located and the effort it takes to fill...If I stop at a truck stop and fill with DEF, I usually have to pull in backwards to get the hose to the fill hole, it being on the passenger side up on the firewall...small little hole so you have to trickle it in...even on the small 2 1/2 gallon size that one can buy at Walmart, Sams, etc....either way,if you put the nozzle down into the hole there's no place for the air to go ...overflowing becomes a issue and DEF is corrosive...after filling, I have to wash off everything because of the spillage.
Lloyd & Kathy & Kit(18 yr old cat)
2014 Forest River Cedar Creek Silverback 33RL
2016 Chevy 3500HD SRW Z71 LTZ 4WD Crew Cab, DuraMax/Allison.
2014 - 38 nights/3500 mi.; 2015 - 66 nights/6260 mi.; 2016 - 44 nights/6106 mi.
2017 - 5 nights/447 mi.; 26 nights booked