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Gl-4 Sae 80 Source...and Even Needed?

Discussion in 'Intermediate CJ-5/6/7/8' started by rusty72cj5, Sep 7, 2020.

  1. Sep 7, 2020
    rusty72cj5

    rusty72cj5 Member

    Florida
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    TSM calls for GL-4 SAE 80 Gear oil for my T15 and D20. Doesn’t seem to be much out there any more though. Anybody find/use a specific one, and is synthetic ok?

    I read a few articles that say avoid GL-5 due to soft metal digestion but that seems to be the bulk of what is available today. Haynes says use GL-5 so another head scratch moment.
     
  2. Sep 7, 2020
    rejeep

    rejeep Well-Known Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Rochester, NY
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    Sta lube makes a gl4 gear oil

    pn 24239
     
    Iandavidh and colojeepguy like this.
  3. Sep 7, 2020
    colojeepguy

    colojeepguy Colorado Springs

    At the foot of...
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    This is what you want. LOTS of discussions about this in past posts! The Sta Lube is on Amazon and it's usually available at NAPA.
     
    Twin2 likes this.
  4. Sep 7, 2020
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member

    Bozeman, MT
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    Sta-lube from napa...
     
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  5. Sep 7, 2020
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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  6. Sep 7, 2020
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Hills of NH
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    Use the GL-4 anywhere there is yellow metal (transmissions, etc).

    Don't listen to the counter guys who say "this stuff is the same." And certainly don't listen to the haynes robots.
     
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  7. Sep 7, 2020
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    And I'd also point out that all the Borg-Warner 3-speeds (T-84, T-90, T-86, T-14, T-15) share oil with the transfer case. You should run the same oil in both units.
     
  8. Sep 7, 2020
    73 cj5

    73 cj5 Not ready for the junkyard yet

    Clinton, Mississippi
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  9. Sep 7, 2020
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    I would not. The Jeep manual says GL-4. That's GL-1.

    API Gear Oil Specifications - oilspecifications.org

    "The designation API GL-1 denotes lubricants intended for manual transmissions operating under such mild conditions that straight petroleum or refined petroleum oil may be used satisfactorily. Oxidation and rust inhibitors, defoamers, and pour depressants may be added to improve the characteristics of these lubricants. Friction modifiers and extreme pressure additives shall not be used."

    My emphasis.
     
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  10. Sep 15, 2020
    officer_friendly

    officer_friendly Member

    Northern California
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    Would GL4 be recommended for a Ford T18 as well? I have never been able to find GL4 so I have been running GL5 for the last 3 years...
     
  11. Sep 15, 2020
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
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    GL-4 is recommended and should be used. They are much easier on the blocking rings (synchronizer rings) and typically shift better with GL-4. NAPA carries it in Sta-Lube brand. It is available online as well. Some Walmart stores carry it and some old time parts houses do. Most parts houses can order it if they can be bothered.
     
  12. Sep 21, 2020
    OnlyOneDR

    OnlyOneDR Member 2023 Sponsor

    R
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  13. Sep 24, 2020
    givemethewillys

    givemethewillys Been here since sparky ran it. 2022 Sponsor

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    I tripped over a gallon of this same stuff for 10 years debating whether it would be fine to use in our transmissions. I finally dumped it at the oil recycler this year.

    I only know that it was 10 years because before I dumped it, I asked the same question you did. And then I searched, and found I had asked the same question 10 years prior, lol.

    I think gl-1 would be fine in the jeep transmissions, but for the price of gl-4, why chance it. Apparently, the original mb's and gpw's used gl-1 in the transfer case/transmission, or so I heard.

    As others have mentioned, sta lube gl-4 is the best bet for keeping your synchros in good shape and having smooth shifting.
     
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  14. Sep 25, 2020
    rejeep

    rejeep Well-Known Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    I wouldn’t use that in any of the BW Jeep gearboxes talked about... that’s a modern day lubricant.. much thinner than 90wt..
    Prob fine for your Nissan, but I would be running a MT90 in a tranny like that...

    I know this horse is beat, but there is only one lubricant readily available on the market for the older BW style gearboxes...

    Sta lube gl4 gear oil
    pn 24239

    Like we should make this a sticky and stop talking about it... maybe get them to be a board sponsor...
     
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  15. Sep 26, 2020
    nickmil

    nickmil In mothballs.

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    This. And well said.
    Beat to death. Well documented. On the same level as knuckle pudding and flat towing.
     
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