OK, I'll take your word for that. All I know about biodiesel is that Willy Nelson uses it in his bus and promotes it on TV. If it works and is practical for consumer and commercial use that's good to know. So many of the new products and ideas in the energy field that are prematurely hyped by the media as THE ANSWER to our energy needs turn out to be impractical pipe dreams that I'm skeptical of all of them until they're proved to be practical.
For one example, not too long ago I watched a news feature on local TV about a CA guy who runs his old Mercedes diesel car on used cooking oil that he collects free from restaurants in the LA area. The reporter's implication was that used cooking oil could be one of the answers to our dependency on foreign fuel sources if only we would all think "outside the box". Now I'm certainly no expert on diesel engine technology or how efficient used cooking oil is as a motor fuel, but I have serious doubts that there is enough used cooking oil produced in a year by all of America's restaurants combined to run even the cars and trucks in one large US metro area for a week.
Well you’re right, there’s not enough used cooking oil to make a lot of difference. But it will work in some VW and older Mercedes diesels.