My 03 savanna 2500 with a 5.3 went 700,000 before it gave up, bought it new had the oil changed to Mobil 1, changed oil every 10,000 miles, and I got 21 mpg from day 1
I find that problem when the pumps have the new nozzle, that prevents topping off the tank, when it does work and kicks off it makes it hard to round off.