Originally Posted by billygo3251
I change it every 4000 miles no matter what. Some may tell you different, but I would go no more than 5000 without change.
It IS listed in your Freightliner and/or Cummins book. I change mine once a year regardless of mileage, although I would rarely be over 5000 miles per year.
I believe they list the INITIAL change at 6 months or 6000 miles. And (according to Cummins) you must NOT extend the time/mileage by using synthetic oil, as in a gas engine.