My current project has been doing modifications on a 2009 GMC Sierra w/ Duramax to see how much I can improve the mileage. I started at 14.5MPG when it was stock. I've got it up to a good consistent 21MPG. A few weeks ago, I noticed all the sudden I was getting 23MPG. Now I am back to 21MPG. Nothing in my driving habits changed, weather was consistent, tires same, etc. Had to be the fuel. I am now circling back to all the places I buy fuel to see if I can figure out where I got the fuel. May have been a fluke.
What part of the country are you in?
Where I am in Alaska we have switched to number 1 diesel, it doesn’t have as much power as the #2 and the rpms drop off a little when I drive with it. But thats in my company concrete mixer with a Cummins ISM.
I don’t know what mileage I get, I also drive a Silverado dually but it has the 8.1L gas motor.
I run a VW Jetta TDI and a 2008 Dodge Ram 4500 with an 11’ dump body and I would love to see better fuel in the US. I can always see a slight improvement in milage and performance when I put in a good fuel Cetane additive, but we shouldn’t have to do this.
I was at a seminar for the new Ford 6.7 Powerstroke engine and the Ford master machanic and rep stated that avg Cetane rating in the US is 38 +-2 points. That is terrible and the main reason for these very expense aftertreatment devices we now see.
I use to get a good 20mpg on my old ‘97 Ram 2500 with a 5-speed and 4.10 rearend, and I’m barley getting 12 (on a good day) in my new 4500 ... yeah it weighs 11,000 lbs, but I should be getting about 14-15 with this if there were no aftertreatment devices.