Ran bio for about a year in a 2003 beetle. Never had any problems till now. I was running mostly B100 or B90 and now and then B20 or regular diesel. Had a seal go on my fuel pump and it won't hold a prime now. The seal happens to be on the spline side of the pump where it connects to the timing belt. I've had two shops say the seal went becuase I ran bio, and one shop said it was more likely regular diesel because they keep cleaning it up and taking out the sulfer, which doesn't allow the seals to season. Either way, it's going to be a heafty repair bill because most places say that part of the pump either can't be rebuilt or it would cost the same to get a new pump, plus they want to replace the timing belt since they have to take it out anyway. Looks to be between $2,000 and $3,000. One place did mention that there are better seals for the pump for biodiesel, but I'm wondering if I should ever run bio again because any little thing in this car costs an arm and a leg to repair. Maybe I should have done more research.