Re: Bio Diesel
Keep in mind that there are several bio-diesels. 'Greasel' uses stuff like used cooking oil directly, but requires modifications to the vehicle. Bio-diesel is processed from non-petroleum products and can be cheap if you do it yourself. However, much of the 'bio-diesel' available from 'traditional' gas stations is a mixture with petro-diesel. It is classified as Bxx, where the xx is the percentage of bio-diesel. B10 and B20 are fairly common; B100 is available but rare; generally only available from a specialty provider.
Bio-diesel, usually B20 +/- is available here and there (I saw it at some gas stations along the interstates, and some towns/cities have specialty providers), but the last time I checked, the difference in price from Petro-Diesel was not very much. And if you use higher than B20 or so, it may void your engine warrantee. Also, bio-diesel has a reputation of being an agressive cleanser, so you may need to change all your filters after switching. Thus switching back and forth may not be practical; a problem in travelling to areas where your supply is unknown.