My truck is an 01 HO, and the very best highway mileage has been 19.5. On the other hand my brother had a 98 with a 24V 5spd and it would regularly get 22 on a long road trip. IMHO towing kills the mileage on all of these trucks. My HO has a 0-35-70 quadzilla chip on it, and in the 70 setting it will do 15mpg on the highway(I won't even talk about towing three horses on 70HP).

 

I think the local station just changed over to summer fuel as I have gone backup to 17-18 on short trips around town and back to 21 for the all high way trip yesterday. This about a jump of 3 mpg across the board. The cold and snow and winter fuel dropped it down into the 14 in town and no more than 17 highway. Easy driving holding it right at 2000-2100. 60 mph.

bentwings

 

Well.
I guess 17 is what is expected with this dually.
I think I am going to sell it and go with a single rear wheel (2500)
I don't even NEED a dually.
I bought it for the looks believe it or not.
They are cool looking and you own the road (seems like)
The heaviest I haul with this truck is my open car trailer and race car.....6000# combined MAX
I guess a dually is overkill.
Anyone out there looking for a Dually????
Thanks for all the tips guys!

 

20.2 on the highway at 65 mph, empty. Measured by record, not the overhead. Consistent.

15.4 on the highway pulling a 6500# trailer at 60 mph.

I've heard a lot variations, and I wonder if these outfits are sensitive to engine mods and driver styles. But I don't believe near-30 mpg.

btw, this is a 4x4 dually.

 

Running lite at 70mph 17-18 mpg, 75mph 16-17mpg, 75-80 15-16mpg. My best hwy MPG without really slowing down is at 68mph just under 2000 rpm. Right around 18.5-19mpg. Computer shows 19.5-20.

You really get to see who's driving what at 68 since everyone goes by in a big hurry.

Dave

 

Yeah and if you bring it down to 50 - 55 MPH (1,600~ RPM @ 55 MPH) you will get 21-22 MPG

I normally set the cruise at 60 MPH in a 65 Speed limit...

And other dayz I will +5 to +10 over speed limit and lose on the MPG!

Out here there is several areas where the top legal speed is only 45 - 55 MPH so why hurry... It only your fuel bill that you will pay! Out here it's $2.749 per gallon!!!

 

You'll be really glad you have the dually in a strong crosswind. Here in WY, that's VERY common, and even guys towing light weights will opt for duallies.

Duallies get slightly worse mileage because of the extra resistance and weight of having 4 rear tires to push.

My 2500 SRW averages 16city, 20 hwy, but has gotten as low as 15 (88mph, brutal cold of 5°F, and stuff in the bed), to a high of 25mpg (52mph hwy, driving like granny on icy roads).

Things you can do to help MPG:
1) Don't use any turbo boost if you don't need it. I can accelerate up to 45-50mph with ZERO boost the whole way
2) Lightweight synthetic gear lube (75w-90 or lighter) will help
3) Tire pressure is huge. Max mpg comes at max inflation pressure, but you will run the centers out of the tires. Try 10psi over what the owner's manual says and you'll be doing well.
4) Wind resistance is huge on the hwy. Slow down. Consider a tonneau cover if you drive over 65mph regularly. Consider AirTabs no matter what.
5) Try a 5W-30 or 10w-30 diesel rated engine oil. Most guys really don't need a full 15w-40, as they don't tow heavy enough. If you are only yanking 6K, then a 10w-30 Rotella or Delo will lube the engine very well and give marginally better MPG doing it.

jlh

 

what are AIR TABS???
I went to AMSOIL in the engine and rear diff.

 

www.airtab.com

 

25-29 is a false reading in the overhead after a box and injectors.

 

The overhead is calculating on average... i reset mine will cruising down the highway and it started off at 37mpg and was like that until i hit the city then it dropped back into the 16-19 range, and when back on the highway, didnt go back up so much.. The overhead lies!

Believe it or not, its aerodynamically proven that with an open bed your truck will get better gas milage.. the air is trapped in the bed and creates a "pillow" of air, therefore all new air from movement goes right over the top of the bed, not in it and slowing you down. I always laugh when i see people drive with their tailgates down thinking they are saving on fuel, when all that does is make the air have to travel through the bed, effectively increasing drag.

Those airtabs look weird.. i million mini spoilers on a truck just dont look right

 

The Cummins engine you have in your truck does not know its hooked up to anything. The tailgate theory really does not apply to a Dodge truck with a Cummins in it. I made a 1000 mile trip to Pine Bluff AK with the tailgate down, when I had one, and with it up. The mpg differance was not worth the ware on the tailgate straps with the tailgate bouncing.

Dave

 

I REMOVED the tailgate.
It is up in the rafters of the shop now.
I am thinking of making a square tube drop-center gate for it.
I have made them for everyone else but me.Everyone likes them...
I guess I should make ME one!!!
DD

 

Sorry to get off topic alittle, but has anyone tried the new amsoil 5W30 series 3000. I got a flier in the mail today and was looking at it and found this new oil. They say it is a good diesel motor oil, synthetic and all. I have just never seen it before. If it will help with mileage I am willing to try it. It is a little more expensive then the regular 15W40 that I have been running.

 

I get (if I can keep my foot out of it) my best milage at 68 MPH. That keeps it just under 2000RPM and then I get between 22-26 (hand computed) on the highway. The variations depend on wind, type of road, and hills. Asphalt freeways seem to give the best milage. The concrete ones give me the lowest.

Over 2000RPM it drops to about 18-19 then comes back up some once I go over 2100RPM.

I also found if I run the cruise control at anything over 80 then my fuel milage goes down dramatically. Dont seet it for 85 cause that is the max cruise will work and the milage is only about 12 MPG and thats empty.

I do clean my IAT quite frequently though.

Phil.