I change the oil myself. Pretty easy on the E450 chasis. Manual calls for every 6 months or 7500 miles. I only put about 3000-4000 miles a year, at most, on mine. With the low usage, I am changing the oil annually (right before I put it in storage for winter) and Using a Full Synthetic Oil. I just can't see changing the oil after it has sat in storage 4-6 months with no use...such a waste! In the event I need to take it into the dealer (recently did for some warranty work), I am lucky enough to have a Ford Heavy Truck center 12 miles from my house.