The owner's manual says you should use Top Tier diesel fuel. The only places it is available in Arizona are two CostCo fuel stations. My dealer did NOT put Top Tier diesel fuel in my "complimentary first tank of fuel" and also did not use the GM recommended additive (or any other additive). This is a significant challenge, as there are VERY few Top Tier diesel fuel sources outside the Midwest. I'm going to have to figure out what additives work, because the AD/Delco additive GM recommends essentially invalidates any cost savings from having a diesel!
thanks, that wait wasn't actually too bad, but I think if we ordered (in early Feb) the wait would have been a lot longer now, if at all - word is they may have stopped taking any new 2021 orders sometime in Jan/Feb, and they have eliminated the Max Trailer package (as well as air-ride package) until further notice due to chip shortage. We would not have been affected by air ride, but we would have ordered the Max Trailer (with Signature package) so chance is our order would have just been canceled.
Would have really liked the diesel, but could not stomach the wait at this point. In the end we are getting ~18-19mpg, which isn't terrible. I feel lucky to have gotten anything at this point - the inventory is pretty abysmal around the country, for what we wanted anyway.
Basketcase, had very similar experience which was all good. Ordered RST with Duramax Dec 24 and received on March 1. Picked up in Texas (no allocation on the Central Gulf Coast) and drove a few hundred miles home with a 27 ft boat the second half of trip.
Observations so far:
Plenty of power on the low end and pulls the same throughout the rpm range, Transmission is excellent and gearing keeps the revs low. Cruises effortlessly at 90 but economy suffers there likely due to high profile. Averages: 24mpg at 90, 26mpg at 70, 27mpg around town, 13mpg towing about 8,000 lbs.
My only disappointment was the suspension which felt tall and "wallowed" a bit. Solved that this weekend with Belltech front springs and OE front springs to the rear. What a nice improvement in ride and handling, firmed it up just a bit. Can't wait for Bilstein to introduce the HD struts for this rig.