I've read that the new engines should not have additives put into the fuel to help with concerns with lubricity. Wouln't biodiesel help with the lubricity and keep the grunge from building up in the EGR plumbing. It has been my experience that bio is really clean burning and hopefully wouldn't have the goo tendency especially in low concentrations ( 2 - 10 % ). I don't trust the fuel these days even with all the hue and cry of how high the quality control on how much is added to make the fuel good enough for these engines.

 

My dad has been using AmsOil Diesel Concentrate in his 6.7. He hasn't seen any faults so far. He does get better mileage with it. It usually bumps from 16 on average to 18mpg.
But I too have wondered the same thing.
Is there any risk to using additives?
I can see how it MIGHT damage all these new emission do-dads and such but I can also see the positive side of it as well....

 

Being the new 6.7L engine was made to burn ULSD I don't see why you would need any fuel additive except to clean up dirty injectors.

 

I've tried a few different brands, most show a little mileage increase, but the best increase was with Lucas, took me from 16mpg @ 75mph empty to 18 mph @ 75mph empty according to overhead (6.7/manual/4x4/3k on clock)