everyone here has given great answers. The #'s assumption is correct. As for the % of BD folks run with and what they say is problematic does depend upon how they drive, where, temps, and quality of the fuel. I brew my own BD at home and run B100 in both mine and Momma's PSD's. I have had no issues related to the fuel or fuel systems. I have run blends again with no issues. I have however run commercially made fuel, and also quality tested it alongside my home brew. Honestly my home brew is cleaner and better quality with a lower cloud point then the ASTM commercial fuel. So my guess could be they have purchased and run lower quality fuels or even had bad petroleum diesel(PD) in their blends and they blame the BD for the problem. Just a guess but thats my answer