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Hemi 6.4, gasoline. 87 or 89.

Discussion in 'Heavy Duty' started by Rwgarrison23, Aug 29, 2019.

  1. Rwgarrison23

    Rwgarrison23 Senior Member

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    I filled up using both gasoline from Shell fuel. I ran 87 and 89. I dont know if it's me but truck seem to like 89 better. What is recommended gasoline for these 6.4? Mines a 2018, by the way.
     
  2. SouthTexan

    SouthTexan Senior Member

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    89 is recommended.
     
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  3. tjfdesmo

    tjfdesmo Senior Member

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    When I had my 6.4 I never saw a lick of difference, even pulling heavy, 23,160 lbs combined. Plus, the RV pumps have diesel and regular, so that's what she got.
     
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  4. Rwgarrison23

    Rwgarrison23 Senior Member

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    I'll drive it a few days and see if I notice any difference going back and forth to work. Towing, definitely I'll use 89.
     
  5. G. Mcpherson

    G. Mcpherson Senior Member

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    When I had my 2016 6.4 I used 89 to start with. Later went with 87 and used it most all the time except when towing.
     
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  6. Rwgarrison23

    Rwgarrison23 Senior Member

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    Also sea level area. I think I'm at 3600 feet above sea level
     
  7. mtofell

    mtofell Senior Member

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    Oh God..... not this again. Last time I think this went about 20 pages.

    Cliff notes:

    -Read the manual.
    -89 octane "may" give a slight improvement in performance and MPG gain but usually not enough to offset cost
    -Some swear there is an increase in towing power but those same folks also believe in ghosts.

    Honestly, I have run a few tanks of 92 octane non-ethanol and gotten pretty good MPGs and power but I think it's more to do with the absence of ethanol rather than the octane. I only run that fuel due to camping deep in the woods and having only one type of fuel available. Otherwise, it's 87 octane regular.
     
  8. Iron Outlaw

    Iron Outlaw Senior Member

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    You know I've ran 87 for over a year straight in mine and coincidentally today I filled up with 89. I swore to myself the midrange felt noticeably healthier on the way home.
     
  9. 1500ram12

    1500ram12 Senior Member

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    [​IMG]


    2018 2500 6.4L Tradesman
     
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  10. Ribtipram

    Ribtipram Member

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    We all know 93/91 is harder to burn then 87 or 89 right. Its a Compression thing. Run the lowest you can unless she spark knocks. Then bump it up one grade. Most likely the 6.4 will never ping off 87 unless its crazy hot out and pulling a heavy load(maybe). Mtofell is right the Absence of ethanol will always bring a couple of mpgs more.anything more then 89 for are 6.4's is a Waste of money.
     

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