lfeather - I change fuel filters every 15,000 miles, or less, by the book. When I had my truck in for new brakes, I asked to get a good look at the location of the fuel filter while my truck was on the hoist. I looked up, but it still looked tough to get at. I think I remember the mechanic saying it was actually easier to climb up into the engine compartment and change the filter from the top. Like I said, under ideal conditions, it still looks like a bit of a PITA. But based on what I have read here, I am going to avoid bio diesel if I can.