Awww, PC. I'm not sure if I should blush or slap you for thinking I was some uneducated, unshaven hippie chick...
Anyways, I can see why you're having failures in the field equipment. Regular diesel, especially from coal (I know, the newer kind is from petroleum and doesn't have this issue, but for the longest time stuff DID use coal diesel), has a lot of fine dust in it: carbon black, bits of metal flakes and some other metals used as anti-knock stuff and engine treatments and what have you. In regular diesel, which maintains a fairly constant viscosity at lower temps, all this stuff sinks to the bottom of the fuel tank/lines/pumps and then stays more or less out of the way of the actual combustion chamber or piston. The carbon black and the dissolved metals are initially soluble enough or fine enough in the diesel that they can pass through the filters, to some extent. Biodiesel, at lower temps than the typical operating temp of the engine, is way more viscous. Any solids in it tend to stay floating around, and therefore if they are not filtered out end up in the combustion chamber. Higher viscosity combined with the manufacturing process (liquid/liquid separation decanting of bio vs. distillation of petroleum-based diesel) means that there will be more water left in the biodiesel, and that is not a happy thing for engines either. It also means that there is a wee bit more compression required to make it go bang, and this is only partially remediated by the improved lubricity. That's where you can see some loss of mileage/efficiency. However, that said, from an engineering perspective this is a fairly trivial problem to solve, whereas the major problems of "Where'd all the oil go?" and "Why are our politicians a bunch of idiots?" are apparently insurmountable.
