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  1. #1
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    Diesel Dually MPG: 6 speed vs 10 speed transmission?

    I have a 2017 F350 diesel dually with 3.55 rear and 6 speed transmission. When I tow, I get around 9 MPG towing around 70 mph. Combined city/hwy without towing get around 16 mpg.

    Looking for comparisons to newer 10 speed transmissions to see if there is a significant advantage when towing. If you reply, please include the year of the truck, gears, transmission, and typical towing speed.

    Thanks,
    Bruce
    New: 2021 Solitude 380FL
    Prior: 2016 Alpine 3600RS
    Tow: 2017 F350 Diesel Dually

  2. #2
    Seasoned Camper Cajun Couple's Avatar
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    Quote Originally Posted by Captcolour View Post
    I have a 2017 F350 diesel dually with 3.55 rear and 6 speed transmission. When I tow, I get around 9 MPG towing around 70 mph. Combined city/hwy without towing get around 16 mpg.

    Looking for comparisons to newer 10 speed transmissions to see if there is a significant advantage when towing. If you reply, please include the year of the truck, gears, transmission, and typical towing speed.

    Thanks,
    Bruce
    I've got the same truck as you but with the 4.10 gearing. I've been getting a consistent 15-16 around town and 17 hwy if I can keep it in the 65 mph range. Towing 9 to 10 mpg depending on speed and road conditions. I think the new 10 speed transmission should help getting a mile or 2 per gallon depending how you drive it. Looking forward to hearing from some 10 speed owners.
    2018 Grand Design Solitude 377MBS

    2017 Ford F-350 Lariat DRW...FX4...4.10's...White Gold/Caribou with Black interior. Curt Q20 hitch. BakFlip MX4

  3. #3
    Rolling Along johndeerefarmer's Avatar
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    Went from a 2016 F250 with 6.7 and 3.55 to a 2020 6.7 with the 10 speed and a 3.31. I gained from 1-1.5 both towing and unloaded. Not sure how much is from the extra 4 gears and changes to the 6.7 vs the change from 3.55 to 3.31
    Donald AKA johndeerefarmer
    2020 Ford F350 Powerstroke diesel
    2017 F150 ecoboost max tow
    2016 Reflection 29RS VIN# 573FR322XG3305717

  4. #4
    Rolling Along
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    4.3 gears and 10 speed and I I get 15mpg avg w/o trailer and about 9mpg with the trailer.

    Wind and elevation change can change the towing mpg avg +/- 2mpg though.

    I can say the 10 speed is phenomenal on hills. I've only felt the truck strain once and that was going up a 11% grade from a stand still (Palo Duro Canyon).

    Newly full timing in our 2021 Momentum 395MS-R with our tow pig being a 2021 F-450 KR

  5. #5
    Setting Up Camp
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    2020 F350 diesel/4.10 rear/10 speed. Towing 395MS-R (around 20K). I get about 10mpg at 63-65 mph.

  6. #6
    Seasoned Camper Sportsdad60's Avatar
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    I just returned from Colorado to Montana, with a 2021 F350 DRW 10 speed trans and 3:55 rear end. (And signature 5th wheel below)

    Altitudes varied between 3000 and 7,800 feet, 2 mountain passes.

    9.2 MPG at 70 MPH on day 1
    11.2 MPG at 65 MPH on day 2.

    I reversed this going home.
    9.6 mpg at 70 MPH on day 1
    11.1 MPG at 65 MPH day 2.

    Without towing I am averaging 17.3 MPG all around use (in town, on the road, 30 miles from our home to town) doing 65 MPH
    Last edited by Sportsdad60; 06-05-2021 at 06:44 AM.
    2021 310GK-R - MorRyde suspension and pin box. Sumo Springs. Solar, 7k axles.
    2019 Lance 1062 Truck Camper, 2 slides.
    2021 F350 Lariat DRW 4x4 6.7 diesel, 10 speed auto, 3.55 diff-48 gallon fuel capacity
    2000 F350 XLT HD SRW 2WD 7.3L diesel, 6-speed manual trans, 3.73 diff - Firestone Airbags-Bilstein Shocks. 82 gallon fuel capacity

  7. #7
    Site Sponsor
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    Thanks for all the replies. You guys are no help ! Was hoping to justify a new 2022 F450 with the wife based on fuel savings! The 1-2 mpg is really about the most I expected and seems is real based on your numbers. I love my F350 too, so I win either way!
    New: 2021 Solitude 380FL
    Prior: 2016 Alpine 3600RS
    Tow: 2017 F350 Diesel Dually

  8. #8
    Paid my dues 😁 FT4NOW's Avatar
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    Quote Originally Posted by Captcolour View Post
    Thanks for all the replies. You guys are no help ! Was hoping to justify a new 2022 F450 with the wife based on fuel savings! The 1-2 mpg is really about the most I expected and seems is real based on your numbers. I love my F350 too, so I win either way!
    Why dont you let her drive your current dually and have her try to turn around in a tight spot, and then do the same with an F450 during a test drive. Tell her its safer too, 450 is higher than 350, so it must be safer, right [emoji16]

    Sent from my SM-G950U using Tapatalk
    2023 Momentum 398M-R
    2023 Ford F-450

    SOLD - 2021 Reflection 311BHS
    SOLD - 2017 Momentum 399TH

  9. #9
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    Dealer is 60 miles away so instead of the normal 70 mph and <8 mpg (lots of hills), I decided to drive at 60 mph just to see how much better the mpg gets. I had tried 65 mph before and was negligible improvement. Got 10.5 mpg so slooooowing down does work. Really boring driving 60 when the speed limit is 70. With the current prices of diesel, may be worth it to slow down on a few trips this summer.
    New: 2021 Solitude 380FL
    Prior: 2016 Alpine 3600RS
    Tow: 2017 F350 Diesel Dually

  10. #10
    Site Team xrated's Avatar
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    I may have posted this info here before, but since you asked, here is the info I have.

    2016 F350 CrewCab Dually 4x4 with the 3:73 rear end and a 60 gallon tank in the bed. Trailer is a 2018 Momentum 394M (GVWR 20K triple axle). My combined weight of the truck and trailer was around 29,000 lbs

    Out west trip last Sept....5143 miles total. Most of that was towing from place to place, but probably 500 to maybe 600 miles of driving without the trailer on the truck. I used the second tripometer for total mileage, which shows gallons used and miles driven. 8.2 MPG for the entire trip. Knoxville, Tn area to Williams, AZ, then to Zion NP, then over to Bryce Canyon, then over to Moab, then headed back home. Obviously quite a bit of mountain driving and elevations out west.....not so much in Texas and Oklahoma. Gallons of Diesel used was 625. So doing the math, it comes out to exactly what the truck's system showed....8.2 mpg overall.
    2016 F350 CrewCab Dually
    2018 Momentum 394M...Heavily Modded!
    2023 Suzuki GSX-S1000 GT+
    Excessive Payload is a Wonderful Thing

    "If it ain't fast....It ain't Fun"

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