happyjack2 - You are getting better mileage of 14 with your 6.0 liter engine versus my 12.1 with my 5.7 liter engine. I always caution people on making judgements on mileage comparison's for one or two tankfuls. I have kept track of every gallon of gas ever burned in my unit and can show where mine has varied from a low of 8.77 to a high of 17.78. The low was pulling a trailer going into a strong headwind and the destination being one mile higher in elevation. The high was returning from the same location, with a 35 mile per hour tailwind and ending 5,000 ft lower. Wind seems to make the most difference.