I use Bio in my 6.4, but im tuned and deleted.....I buy B-99 and mix accordingly. I am running B-20 right now and have been for months, not a single problem. I did the same thing in my 6.0 with no issues ( one gelled filter in the winter from running to high a concentration) But my truck runs perfect and I have changed the fuel filters once and they looked great!

I think the key is the fuel you buy, I buy my Biodiesel from a commercial maker ( newport Biodiesel) and its made great!