We run Bio-diesel in our 1999 Freightliners, and have a hard time making 10,000 miles before we change the fuel filters. Winter time it's a lot worse.

We go thru filters like crazy pumping Bio-Diesel out out of the ground, when the temperature is below 40 degrees.

 

Get a Davco primary fuel processor. you can see the filter thru the cover. When the fuel reaches the top of the filter, change it. No use wasting perfectly good filters when you don't have to. I have used Davco systems on a lot of trucks.... Detroit and Cummins engines with great results. It has a fuel heater element for cold weather as well. I usually use a 15% biodiesel blend. I had to change the filter a couple of times rather soon until the Biodiesel cleaned out the tanks and lines. Now filters are lasting 40K miles.

Just an FYI.