After talking to some folks here and doing other research, I decided to run biodiesel in my 1996 7.3l Powerstroke. Yesterday I went to a nearby Propel Biofuels
station on two quarter full tanks of petro, and filled them both with B75 from their pump.
I drove five miles or so with no issues, stopped for a couple hours, then drove four or five more miles. Engine ran the same, but towards the end of the second leg the "water in fuel" light flickered on briefly as I climbed a hill. This was maybe a quarter mile from home, and it blinked again and then seemed to go on steady when I stopped in the driveway.
Any thoughts on this? I know the bio has a solvent quality that can break down gunk. Could water have been released from somewhere, or maybe the sensor got clogged?
I think I was at the bottom of the pump's tank, too, if that makes a difference. It seemed to slow a lot at the end of the second tank.
This fuel is supposed to be a quality product, so hopefully it's not truly water in the fuel tank, but a false reading of some kind.