I see no visible smoke difference. I figured by the time they truck it store it take it to the refinery, refine it and truck it back to the pump.. I'm probably putting out less emissions per gallon..lol as a side note, this being a military truck is emissions exempt. 4.56 gearing, no overdrive and 37 inch tires. 1 1/4 ton rating.. I'd be saved say the old girls probably still doing 13 or 14.