I have a 6.7L F250 now and get from 12-19MPG with overall avg. of 16MPG. Hoping to improve 5+ MPG on new 3.0L. Could current or past owners give me some input? Also, does anyone use Standyne, AvOx or any other additive and will that help MPG? My ordered truck is coming with 3.31 axle ratio also.