yea, i went from bio, to normal diesel. i drove it 400 miles on regular diesel without a hitch. then i get home and drive it around for a couple days and i notice air bubbles in the fuel line. but i didnt really think much of it since it still ran and revved up and made power. but anyway, went to start it the next morning, and there was nothing. and my prime from the tank was gone. so i tried to re prime, but that was a no go. so, next i pull the filter, and voila, it was 3/4 full of nasty brown/black gunk. smelled really bad too. and it was really thick like grease. but now my tank is full of red fuel and my car is lovin it. starts cold every time with ether assistance. i know its a no no, but it wont start any other way. its not my fault my car has to get drunk before it will start!