natescape:I know b20 should work with no problems, as many big agencies (like the FDA, I believe) use b20 to power their generators. Higher blends ... I dunno.
My guess would be that
1= someone has to make sure that there is no natural rubber compounds in the fuel flow path.
2= someone has to make sure that whatever injects fuel into the combustion chamber is properly modified to deal with potential problems due to biodiesel.
3= Fuel filter systems might need to be modified. Or at least their maintenance schedule.
4= Manufacturers will probably want to publish some legalese regarding biodiesel's cold temperature characteristics and to only use ASTM certified fuels to CTA ("Cover Their ...)".
Once all that's done, There should be no problem using even B100 in just about any diesel engine.