I have not had any problems with filters since using biodiesel, but what I did have were leaks. First the injector return lines, then the primer pump, then the supply lines, then the tank lines, now the injection pump seals. However, my car is old and perhaps they were all needing to be replaced anyway, though I suspect the bio accelerated the process.

I've also never used more than 75% bio. Usually I use B20 or mix my own between B5 and B50.

__________________
1976 240D "Katja"