I have made and run a few tanks of b100 (100% bio) in the Big Unit. Its not big deal. As far as the injectors know, its the same as dino-diesel.
What the issue is revolves around a) the almost total lack of sulfur, which can be offset with a suitable fuel additive, and b) Bio-diesel has a bit of a solvent-effect. If you have an older truck, that effect can dislodge the gunk in your fuel system and potentially clog your fuel filters.
BTW, bio isn't free and its not junk. A friend and I had a working appleseed reactor to make bio-diesel. Provided you wash and dry the resultant product properly, it is actually very high quality. As we could not secure a reliable source of feedstock (waste oil) for the reactor, we gave up on making Bio.
Also, living in Jefferson County MO (The meth production capital of the USA) a functioning Appleseed reactor in the garage with all the paraphernalia causes the neighbors to make anonymous phone calls and you get a nice visit from some very stern deputies.
At any rate, don't fret the B20. It's not like the ethonol in gasoline situation that was killing fuel systems. Just use a good fuel additive like Stanadyne Lubricity formula.
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