I ran all my diesels on B20 for about 2 years, will no adverse effects. The only reason I stopped, is my fuel distributor doesn't like having to blend it, or mess with it. Not because it's bad, they just don't seem to like the extra work it involves, between physically blending it, and then filing for the government rebate makes for extra paperwork. So they either don't carry it when I need it, or have priced it to make it unattractive. It ticks me off, because everything was running good on it, and it creates a higher demand for one of the very crops I grow - soybeans. 

The only downside I came across was the smell of the exhaust always made me hungry. Smelled like chicken being cooked on a charcoal grill.