Not sure if there's a better place for this question, but how much does the winter diesel affect mileage? Mine seems to have dropped from 24 to 19 on the DIC all in about 1 tank of fuel. Nothing else has changed with the truck. Thanks, Craig

Thats alot. There is something else going on. 2-3mpg is normal.

Thanks, thats what I thought. One other time this happened it blew an intercooler hose off and was leaking boost. Checked all that and everything looks good there. We did just get back from a 500 mile trip pulling a trailer, maybe it still needs to 'relearn' or something?? Weird.

on ours, if you don't reset the mileage after a long trip of pulling a trailer or something it takes a long time for the mileage to show back to 20 or whatever it gets empty because its still counting miles from the previous trip. with the mileage thing on the screen, try holding the back arrow on the steering wheel till it goes back to zero then drive it and see what it says

I've re-set the DIC twice now just to be sure.

Have you been idling more? Driving it alittle harder? Driving more city? Mine does the same thing, i can get really good on some tanks and then not-so-hot on others. If you haven't changed your driving habits than i would say that its just the fuel.

I average 17mpg average and 15.5mpg average on winter blend. Staight highway in summer I do about 19mpg with current tune. Have seen better but like current tune. But not sure if you are letting it warm up and if so that could be part of it as well.

Brian

Yeah it has been cooler lately so maybe with shorter trips lately it hasn't warmed up enough and affected the mileage too. Could be a combination of things I guess.

Summer fuel I get 18-19mpg, winter fuel 16.5-17.5, but some drop is because in the winter it idles for 10-15 minutes most days before leaving. Like to get it a little warm for the kids.

don't forget to check tire pressure. for every 7 deg F I think it varies by 1 psi.
how about using some cetane booster addi?
I saw amalgamatedinc tdrs give a 6+ boost.
anyone tried a cetane booster and is it worth the $$?

checked the bottle kleen white,
cetane boost 6+
mileage inc 8%

I regularly use the cetane booster called Diesel Kleen I think in the gray bottle.

I think mine has dropped from winter fuel too. However I did get a heavier foot about a month ago. But have been working on that one.
I will also add, between idle time and driving habbit's I have got between 13 and 21.5 mpg's.
These trucks or atleast mine can be sensitive to the way you drive as far as mileage.
If you want your best, if you have a boost guage, you can watch if it goes up, more air more fuel. I have gotten the best mileage with no boost.

I believe our winter fuel blend usually starts around Nov. 15.