My 2012 Cummins I replace the fuel filter every 10k miles at 59.00 dollars. Oil change every 6000 miles at 14.00 for the filter, and about 45.00 for the oil. Air filter was 26.00 and I replaced it for the first time at 19000 miles. There really isnt any other maintenance different than other vehicles. Sure the diesel takes 12 quarts compared to maybe 6 or 8 in a gasser. But you also dont have spark plugs to replace so Im not real sure where all these super expensive diesel cost rumors come from. Maybe if you paid people to do it. Prices I quoted are all me doing the maintenance. Draining the water separator is as easy as turning a knob. Takes all of one minute