After more than 6 months everything has been great since I replaced the fuel filter back in Feb. without any further problems. I found out that you cannot mix a fuel additive with BioDiesel and not use immediately. If the biodiesel sits by itself there isn't a problem, but if I add a fuel additive it causes a seperation and a good 3 inch layer of sludge in a gallon mix if it sits for more than a month.