Our local Ford dealer says that FMC says that B5, 5% biodiesel is the maximum safe percentage allowed in our engines. Is there data out there that indicates that is safe to run higher percentages of biodiesel in the 7.3's? My truck gets driven about 6K miles per year, usually four 1200 mile trips a year, and some local driving. Obviously, I do not fuel up very often. It is running on a tank of fuel bought in early December, and I will probably buy fuel again in February or March, so I am concerned about fuel stability as well. I change the fuel filter once a year, and drive the truck about 10 miles once a week, and have had no problems running #2.