This site is awesome, I just bought a 2007.5 2500HD z71 extended cab LMM. I purchased it last week while I was on a camping trip and my big block suburban engine blew and left us stranded 3 hours from home with my 30' travel trailer. I have a question about the fuel, is all diesel fuel ultra low sulfer (15 ppm)? I had to fuel up on the way home and that pump said 15 ppm but most of the pumps in my area say low sulfer 500ppm. Since I only have 300 miles on the truck I don't want to make an $$$$ mistake and damage my baby.