Hello again. This one has me a little stumped... My old man took a trip from Nebraska to the Can. border a couple of days ago to pick up an old tractor when the temps were below zero. We guessed the tractor to weigh about 15K and I'm not so sure about the trailer. Its a triple axle gooseneck approx 30ft long. When he returned, he was complaining about only getting 5-6 mpg towing home. He ran winter blend in one tank and was using a fuel addative (It looked like some generic type to me as he doesnt usually use addatives at all) but the rest of the time it was plain #2. Could it just be the weight and the cold temps? Hell, at 5-6 mpg our 6.0 gasser is (A LITTLE) better! :eek: I know his fuel pressure regulator isnt the greates as he has a pretty lopey idle most of the time but GM says it isnt bad enough yet and I dont think that should affect this. Any sugguestions?
Thanks, Jason

I'm not towing anything however when the pumps are switched over to blended fuel up here my mileage does take a dive. That along with the cold will do it. I run additives all year round but usually when Nov. comes around mileage suffers. I lose on average 60-70 miles per tank.

My friends 32ft tandem axle gooseneck is 7900lbs, so yours most likely is in that range. So 22900 plus the truck and cold weather, milage seems low but thats a pretty good load.

I see my milage in the 9mpg range during our harvest. That's not towing anything! But that's driving in 4x4 and in loose sand and quite a bit of idling.
When towing I see anywhere from 7-12mpg depending on loads and how heavy the foot is. (usually heavy!)

Never really took a long trip without towing anything but to town etc (18 miles) I get up to 13-14 mpg.

I still don't believe people get over 20 mpg out of these rigs. Out of the 4 trucks we run with the DM/A none of them get over 17 mpg.

I think it's weather, terrain, and steady driving... When I got 22 MPG last I was in georgia, and it was all freeway miles from atlanta... very few hills.

I got 32 mpg for 400 miles from hwy 16/Interstate 94 to Fargo, ND. 400 miles on a half tanks worth of fuel. That was the grace of God with a 45 MPH tailwind.

Personally, I am getting around 17-19 depending on terrain, cruise control, etc. I also had an empty truck.. completely empty, for the 22 MPG... she was brand new.

I don't see that anymore though.. wish I did.

Yeah, I know I was pushing 20 mpg with my stock tires, now I'm about 17 mpg and dads has been running at around 15-17 with some idling and some stop and go and most of his travel is on gravel. We were just a little suprised on the highway trip. It may just be that the trailer pulls a little hard...
Jason

Did he have any kind of winter front cover on the truck? I don't remember if it was supplied on the 03's but with my 01, it gets better mileage when running warmer. Without it Friday morning, early, temps in the teens and 20's I was only getting 15, usually get 18 on the same trip in the summer. Temp gauge was halfway between 210 and the low peg.
Then too, I think all northern fuel stations blend their fuel in the winter, and none of them post a sign about it...

He had the winter cover on going up with the empty trailer, but took it off for the trip back because he thought the cooling fan was kicking on too much....
Jason

Personal experience

If you use 2 or more different additives in the same tank of fuel you stand a chance of the additives mixing and congeling. if this mix should get to the filter, you might have a problem, sounds kind of far fetched but posible.

also additives can disolve some plastics. have seen that happen too.

drive safe.

I see my milage in the 9mpg range during our harvest. That's not towing anything! But that's driving in 4x4 and in loose sand and quite a bit of idling.
When towing I see anywhere from 7-12mpg depending on loads and how heavy the foot is. (usually heavy!)

Never really took a long trip without towing anything but to town etc (18 miles) I get up to 13-14 mpg.

I still don't believe people get over 20 mpg out of these rigs. Out of the 4 trucks we run with the DM/A none of them get over 17 mpg.
I'm with you on this one. Running empty in warm weather back and forth to work, I see around 16 mpg. Hook up the camper (travel trailer not 5th wheel) and I'm seeing 10.5 to 11.5 mpg.

Now with no trailer and all highway miles, I could see the mpg going to the upper teens, but sorry to say I have a hard time believing people getting over 20 mpg consistently and an even harder time believeing people are getting the 12 to 14 + mpg pulling trailers.

LARSONEM, believe it or not some do get better than others. There are a lot of things that help or kill your mileage. I have kept a running spreadsheet on every gallon of fuel that I put in my truck since new. For 47K miles running solo my average is 18.54. For 11K towing my 10K pound Wildcat the average is 12.02. I can count on one hand the tanks I averaged 20 solo or 14 towing. I can get 20 anytime I want to drive under 60 for a full tank. I have The Juice but it doesn't help solo but does towing. Later! Frank

Thanks guys, thats some good input!
Jason

My 03, CC with allinson and 265 tires, averages:

empty/summer - 17.5 - 19.5 (city/highway)
empty/winter - 15 - 18
towing 4000 to 8000 pound trailers - 10.5-11.5

Only seen 20+ one time, and that was all highway driving in the 60-65 MPH range.

Winter driving in the 45-55 range in 4wd, the MPG's really drop off, even with the winterfront on, the truck never really warms up.

The wind drag from the trailer seems to affect the MPG a lot more than the weight...

5-6MPG, even towing something that big, seems really low, unless there is extra drag in the trailer (wheel bearings?) and/or a strong headwind or a lot of uphill sections....

In florida on the flat lands travelling at 55 mph towing 10,000# and no head winds I have had 14 US.mpg. many times, no lead in my feet just feathers.

drive safe.

I pretty sure I figured out the MAIN cause for the poor mileage. I had a little time on my hands today so I took a look at his truck. First thing I noticed was that the air filter minder was pegged red. Opened the cleaner box and found the problem. The filter seemed to be full of mud (or what used to be mud). Either he had a lot of dirt in there and it got damp and wet and turned to mud or else he somehow got mud into the intake through the wheel well. I should have known to check this right away as he is oblivious to the fact that our stock air boxes seem to be a magnet for mud/water/dust from the wheel well. I'm sure this had a major effect, especially when towing...
Just thought I'd post what I found.
Jason

A few observations on milage. I've been keeping track of milage on my 89 CC Dually BB gasser for over 10 years and one of the biggest factors on milage (all else being equal) was tread pattern. A straight highway rib gave the best and going to even a moderate block pattern would loose 1.5 to 2 mpg. 4wd, the number of tires on the ground (soon to be tested), speed, weight, towing, etc, etc... all have a large affect. I just took a trip to Phoenix and back, tailgate down, speed limit +5 Juice on 1 and got 16.6 with my 03 EC 4x4 Dually Duramax. Leaving Friday again but this time with only the outside dual, we shall see if that makes a difference.

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03 EC 4x4 Dually Duramax, Juice / Attitude, Amsoil bypass.
83 Elco LT1 4L60E

Best I got was 19.8 empty highway was driving between 60 and 80. Had some traffic slow downs. Tailgate was down and I had a slight tail wind. I was also easy on the pedal from stops. I usuall drive a mix of city/highway and get 17 almost reguardless of how I drive. I try to keep it below 75 because I have seent that constant 80+ eats the fuel up. The city/highway is with the tail gate up. I think that empty on a good highway run with the tailgate down and not head wind that 20 is doable I have just not seen it yet. I als get around 14 when pulling. I have not pulled anything super heavy yet so my pulling mileage is not to accurate. But light trailers at 75 to 80 I am sure I eat enough fuel as if I was pulling 8000 pounds at 65. Just a guess. She has a few 10,000 pound pull jobs coming up this spring so that will be a nice test.

Just checked my database, a short trip with my 11' Lance and towing the boat that weighs 8000, got 9.4 at 75mph. Camper alone gets about 10.5. So far the only way I know to get good milage here in Colorado is to always drive downhill. I know that if I would slow down a bit it would go up but what's the fun in that?

My 2 cents worth - Day in day out, I get 17 MPG going down the highway empty, until blended fuels come out in the winter. Depending on the station (and the blend), I have seen 2-4 mpg drops.

When I tow cows in a 20' gooseneck, ~ 15k, my mileage drops to about 11-12 on the highway. However, if I were to push it and try to stay at/above the speed limit, I would then drop into the 8-10 range.

So adding up your weight, winter fuels, and if you don't take it easy with that heavy load, I can definately understand the 5-6 MPG range.

I agree with drhutch. I've never seen a great gain or loss with my Edge Comp box, 80hp injectors, or my 130hp injectors. But my truck consistantly saw losses with the addition of my lift, 295 tires, and now my 315 tires. Can't have everything I guess!