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MPG difference between 3.08 and 3.42 ratios

Discussion in 'Engine & Drivetrain' started by Tiredmechanic23, Jul 3, 2020.

  1. swathdiver

    swathdiver Full Access Member

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    I reckon those Amsoil products are worth at least 1 mpg Robert, great stuff!
     
  2. Bob2C

    Bob2C Full Access Member

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    I think so. I am also running AMSOIL xl in the engine for the first time. I think I would be waisting the signature changing it out at 6k mike intervals. I still run the ac Delco PF63e. I’m happy


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  3. exp500

    exp500 Full Access Member

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    Alot of discussion on gears no matter which section of forums you are in..... Mileage, performance, towing, Offroad. Simple explanation is 308/342/373/410/455 - each step is about as close to 10 percent as you can get- So any changes one step will be minimal, about the same as 2 different drivers. Takes a 2 step jump to be significant. So in the end it comes down to how you drive. Over 80 need 373 or less(engine RPM). Always remember, the faster you spin driveshaft, the more relible the driveline is (less stressed).
     
  4. 59yukon01

    59yukon01 Member

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    Have a 2016 Yukon with the 3.42. Last trip from KY to FL and back I averaged 20-21 on the hwy, but that was at pretty much a constant 80 MPH.
     
  5. stallion_412

    stallion_412 TYF Newbie

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    2015 Yukon 4x4 5.3l engine w/ 3.42 rear end. Average 23-24mpg at 75mph.

    What really surprised me is how much better it is than my pickup which has the same powertrain. My pickup only gets ~19-21mpg at 75mph, depending on a lot of conditions.
     
  6. BG1988

    BG1988 Full Access Member

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    tell gm so it can come with it from the factory
     

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