Allison Transmission

[Traveler II]

I understand that the milage improves after the diesel engine is used. On average how many miles on the truck is needed to see improvement? We have 28,000 miles on our 08.

I was told by an over the road truck driver that his diesel broke in at 100,000 miles

[Mike Clay]

Mine was around 18k have 32k on it now, mileage went up and power came up. The best mileage so far was 21.7 all freeway under 65 mph the best towing was 14.2 i average around 11 to 12 while towing. These are all numbers from a fresh fill up and hand calc. In my case when I bought my truck i had to get 500 miles on it real fast in fact we did it in a weekend. We had a trip planned the following weekend with the trailer, then came the Albq. Rally when we left home the truck only had 1700 miles on it.

The same held true with all 5 of my Dodge CTD trucks seemed to be right around 20k.

[tschmalz]

It would be interesting to find out what speeds people were towing at when they calculated their MPG. It sounds like most are towing between 65 and 70 mph. Most everything I've read about towing discourages traveling at anything above 65 mph for an extended period. I'm not sure about other states but Calif. speedlimit for vehicels towing is 55 mph. I know this is a little slow, and most won't follow it, but 70 mph seems a little high. I think the bottom line is, if you want better fuel economy you may have to slow down a little. This also brings up another side issue, tire failures. Most are related to tires over heating which is directly connected to the speed at which the vehicle is traveling.

[Rob & Cathy]

It would be interesting to find out what speeds people were towing at when they calculated their MPG.

I find that when I'm on the open road I set the cruise control at 2000 RPM and that equates to around 63-64 MPH.

Rob

[Traveler II]

I set ours at 1800 RPM and that around 60-62 mph. I get around 11-12 mpg.

[Mike Clay]

Not sure what my rpm is but I will take it to 65 let it go into 6th then travel around 63 mph.

[surveyman]

1800rpm is 67, 68 in 6th. Under normal driving the rpm's are always between 1500 and 2200 in every gear with my Allison.

[Don Wilson]

I drive a 06 Dodge 3500 dually with the 5.9 Cummins and use tow haul mode and run between 1,800 and 2, 000 rpm which equates to 63 or 64 miles per hour. I average about 11.3 which means I get about 10 pulling hills and the best I get is 13.4 on flat land. On the Rally trip last fall from Durango Colorado to Vidiala Louisiana and then back to California we drove 6,200 miles on the trip and averaged 11.3mpg.

Don

[Traveler II]

Tried something new today. After getting up to speed on flat roads I turned the tow mode off. The transmission moved to 6th gear and the RPM dropped. I put it back into tow mode when we were getting into city driving. Not sure I will stick with this, because knowing me I will forget to put it back in when I need it. But it was interesting to see what happen.

[Jash]

I leave mine in tow haul and just increase the speed till it shifts to 6th gear, then i just slow down to about 62 at which time the rpm is about 1600. That way if I come to an hill it will down shift sooner.

[Mike Clay]

I do like you John then when going up a hill i tap the throttle to let it shift to 5th then at about 58 mph i tap the throttle again on long pulls to let it shift to 4th and hold the rpm at 2300. I find at that rpm the water temp, tranny temp and pyro temps come up a lot slower and do not get into a high heat zone. Guess im a control freak i would rather take charge of the temps before the computer does, and it starts de-fuling the engine or worse yet engine limp mode or tranny limp mode.