I'm new into Diesels. I bought my first back in July, an 02. When I first got it I was getting just under 19mpg. In the past couple of months its dropped big time, down to 14-15. Does the cold affect milage that bad? Or could it be from additives in the fuel? I stopped at the dealer and he said I wasn't the first person thats complained about it so far. And their isn't nothing he could check unless the check engine light was on, don't know if that true ot not. Just curious if theirs anything I could do. Thanks for any info.

This time of year you are burning #1 fuel instead of #2 to prevent gelling. It has less BTU's and therefor you will have less power and worse fuel mileage.

I have my front cover on and I feel that increases drag too. As Max said above that the fuels suck right now and that will hurt your MPG substantionally.
Ben

I was told by my dealer that sudden loss of mileage is a sign of early injector failure. It is one of the criteria for injector replacment according to them.

I was told by my dealer that sudden loss of mileage is a sign of early injector failure. It is one of the criteria for injector replacment according to them.

You should be getting a new set every winter then mate. :)

Just checked mileage with the last tank....still 16 mpg in town. Fuel station doesn't even know what #1 diesel is....never seen it.

Of course, it was 68F yesterday and sunny. ):h

Happy New Year!!

I've been 11.5 mpg my last 2 tanks. I'm really dissapointed with that. I almost HOPE I have injector problems. That way things can only get better. Considering my truck still wont start below 20 deg after sitting for >8 hours there has to be something wrong.
If any more problems pop up I will sell it before the warranty runs out.

My last 2 tanks have been in the 14-15 mpg range. I have noticed a drop in mpg each winter when the fuel gets switched over.

Ok, that sounds about right then. I only got 20,000 miles on mine so far. If their would be a problem, would I be experiening it this soon? Not saying I do have a problem, just curious on how reliable the injectors are.

Kurt, what tires did you have on when you got 19? We run blended fuel here starting in mid Oct. My average goes down approximately 1.5 MPG until sometime in Feb. Later! Frank

I'm down from 19-20.5 mpg to 17-18 mpg per tank, since last week of November. I'm assuming thats when the winter blend fuel started showin up here in the NE.

JJ

My 02 has been using more also...just a poor quality fuel...even smells different....winter fuel is very thin so not much we can do. Still have the power though ):h .

happy new year everyone.


02 GMC 4x4 extended S/B D/A, Indigo Blue, SWISS CHEESE AIR BOX, HIGH IDLE THAT I INSTALLED, NERF BARS, BRUSH GUARD, EVERYTHING ELSE STOCK

My milage dropped like a rock too.....was at an honest 20mpg....now, I'm closer to 14.....damn winter fuel..:(

Frank, At the time I had them little donuts on it (245's). But I didn't get new tires til about 2 weeks ago which are now 285's. So I did notice the drop yet when I had the 245's on it. I did notice a bit of a drop too with the new tires but I haven't calibrated the speedo yet, so it may not have changed too much.

My 05 2500 D\A CC LB bone stock gets 14.9 mpg :( It has 1000 miles on it.Censored One of the reasons i bought a dmax was for better mileage ( I got 14 in my 02 chevy 5.3) but u guys say its the winter fuel...

No sir. Im still doing some work, but the truck is loaded for only 5 miles or so.

Havent fallen off of my 19-22 mph avg.

No winterized diesel here!!!

Right here in NE CO 10 miles from NE either way everyone has had a lot of power complaints with their equipment. More so than other years. Conditions where tougher but also shot a few fuel pumps. Started blowing fuel by the barrels or seals failing in the gear pumps. They ran well into the blended fuel season and I'm not sure the quality is there this year. Probably a good year to run a bottle or two of addative till we hit summer fuel again.

A lot of guys have posted a loss of mileage with the 285s. I am sure someone can give you the correct multiplier for them. I am sure it is 6% or better. Later! Frank

You need to get at least 12-15K miles, sometimes closer to 20K before the engine is broken in. That is when you will get better mileage.

285s need about an 8% correction, I use 9% for my 295s. I have an '02, and have lived in San Antonio and now Tucson with this truck. My best mileage ever was 21.9, with 285s and 1.75" of T-bar lift. That was at around 65-68 MPH. When I drive around 70-73 mileage drops, and it drops again at 75-78. My truck now has a 4" Rancho lift, and the extra 2" of height seems to hurt mpg a little--my guess is .5 to 1 mpg at freeway speeds.

Right now, with BFG 295s and the Rancho lift, I get 19-20 if I keep it under 68, and 16-17 at 75-78. During a recent trip on I-10 between San Antonio and Tucson I was driving at 75-78 and was bucking a headwind--my guess is 15+ mph. I averaged 16 mpg that trip.

I also noticed significant increases in mileage at around 5000 miles, and then again at 18,000 miles.

I too have noticed a drastic decrease in my fuel milage starting the last weeks of November here in Maryland. My 04.5 was getting about 18 mpg ):h combined city and hwy. now its 15 mpgCensored . I have 25000 miles on it.

Cosgr:D ve

I too have noticed a drastic decrease in my fuel milage starting the last weeks of November here in Maryland. My 04.5 was getting about 18 mpg ):h combined city and hwy. now its 15 mpgCensored . I have 25000 miles on it.

Cosgr:D ve

Ditto....went from a steady 17 in mixed driving to 15.5 now. I'm sure warm-up idles are partly to blame.

Kurt where are you located? If you don't live in a cold climate you won't be getting blended fuels. However I noticed a drop when Memphis had to start using the ultra low sulfur diesel. I was up to around 18.5 hwy and 15 city, but after the change about 17 hwy and 14 city.
To tell if you're getting the ultra low sulphur fuel just look at the stuff, if it's clear and you're in a warm climate, it's the ultra low $#it! We had to start using the stuff because of the EPA's air quality standards.
I got a tank of the regular #2 a couple of weeks back and thought I'd died and gone to heaven, there was that much difference in the fuel.
Doug

I'm in southern Illinois, about 40 miles south east of St.Louis. And it does get pretty cold at times around here. And all of the fuel is #2, don't think I've ever seen #1 come to think of it. I'll need to fuel up in a day or two so I'll check the color out.

Around here we have no choice at all. They blend it for us and we never know what we are getting. The pumps are marked diesel and that's it.

My milage dropped to about 15.5 (DIC) after weather turned cold and winter front was installed. Weather went to 60+ took cold front off and milage went back up to 19.7 (DIC)
go figure? Engine temps stayed just about the same. May have something to do with intercooler efficiently cooling turbo discharge air, cooler air= more dense air= more power. Come on Spring/summer.