1st DEF fill up
Filled the DEF for the 1st time today. Took 4.2 gallons. Mileage was 5400. According to the calculator, that equates to just under 1300 miles per gallon. Dash info center said I had 470 miles left on ...
Forum Discussion
I use about 5 gallons of DEF on my 2015 denali between oil changes at around 6500 miles. GM says they sized the DEF tank to require filling about every oil change. Going by the oil change interval reading, I'd say they are close but a little optimistic on the DEF tank size.
