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Syncromesh

Discussion in 'Early CJ5 and CJ6 Tech' started by 3b a runnin, Feb 29, 2016.

  1. Mar 30, 2016
    Dave B

    Dave B Frankenjeep '67

    Northern Minnesota
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    BSweet, would you check and see if Napa brand 80W90 is compatible with yellow metals (brass and the like).

    I'll step out here without personal experience, but what I've gathered from EarlyCJ5, as well as other sources, GL - 4 is the recommended rating for, shall we say, "classic" synchromesh transmissions. I'm understanding that GL- 4 is right for brass synchronizers, and that is GL - 4 specifically, not GL- 4 included in combination with other ratings such GL- 5.
     
    Last edited: Mar 30, 2016
  2. Mar 31, 2016
    Rick Whitson

    Rick Whitson Detroit Area 2024 Sponsor 2022 Sponsor

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    They opened a Tractor Supply by me, I love it, I am amazed by what they have there. It is worth going to just to look around.
     
    Hellion likes this.
  3. Apr 1, 2016
    BSweet

    BSweet New Member

    Garrett, Indiana
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    I used Napa 75-210. GL3,GL4 and GL5 API rated. Says it is for use in manual transmissions and axles. I think it was better than the 50 year old looking stuff that I drained out of everything. Had to literally scrape the old gear oil out of front differential!
     
  4. Apr 2, 2016
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
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    That's fine for the differentials and transfer case but not for the transmission. The GL-5 rated stuff is not good for these old transmissions. You want the GL-4 rated stuff.
     
  5. Apr 2, 2016
    uncamonkey

    uncamonkey Member

    Greeley CO
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    I suppose that's why I have about 4 gallons of it out in my garage. It took me a few years to catch onto the difference between GL5 and GL4. The guy at NAPA thought I was nuts. I had to explain it to him. I'm sure he still thinks I'm nutso.
     
  6. Apr 2, 2016
    47v6

    47v6 junk wrecker! 2023 Sponsor 2022 Sponsor

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    Yeah, I went through this same issue with a couple local auto parts houses. I gave up and just ordered it from amazon.
     
  7. Apr 2, 2016
    BSweet

    BSweet New Member

    Garrett, Indiana
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    I will see if I can get anything that is straight GL4 rated. I work at a Napa store myself!
     
  8. Apr 4, 2016
    Rick Whitson

    Rick Whitson Detroit Area 2024 Sponsor 2022 Sponsor

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    I just bought five quarts from Napa three or four weeks ago. Sta-Lube it is called. GL 4
     
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  9. Apr 6, 2016
    BSweet

    BSweet New Member

    Garrett, Indiana
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    Never thought of Sta-Lube brand.
     
  10. Apr 6, 2016
    47v6

    47v6 junk wrecker! 2023 Sponsor 2022 Sponsor

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    me neither, but it seems to be the only available one making GL-4
     
  11. Apr 6, 2016
    homersdog

    homersdog Tulsa, Ok 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    Its not cheap, paid 36 about 3 weeks ago.
     
  12. Apr 6, 2016
    SFaulken

    SFaulken Active Member

    Bellevue, WA
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    Apparently Redline MT-90 is another good option, if you want to go the synthetic route. And pay the synthetic prices.
     
  13. Apr 7, 2016
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
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    I haven't tried the Redline but I've had bad experiences with other synthetics in a transmission that requires GL-4. Caused all kinds of hard shifting and grinding issues. Too slick for the blocking rings to cut through the oil film and grab the cone of the gear like it needs to do for proper shifting. This is one of the problems with using GL-5 in these transmissions.
     
  14. Apr 7, 2016
    Rick Whitson

    Rick Whitson Detroit Area 2024 Sponsor 2022 Sponsor

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    5 quarts of Sta-lube was over $50.00, but at least I got what I was advised to use by the people that know on this site.
     
  15. Apr 7, 2016
    colojeepguy

    colojeepguy Colorado Springs

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    There's a Motorcraft full synthetic 75W90 full synthetic oil that's GL-4 rated. I tried it in my T-90 and it behaved much as you describe.
    Switched back to the StaLube GL-4 dino oil and no problems....
     
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  16. Apr 7, 2016
    mike stg

    mike stg Member

    gilbert AZ
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    All this talk of oils has me wondering..... is the problem that it will grind going into 2nd or 3rd, or is it a problem that it will pop out of 2nd or 3rd gear?
     
  17. Apr 7, 2016
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    Too slick will make it grind. The brass blocking rings have to grab into the gears so that gear speed matches. No matching makes gear clash.

    I expect it will not effect whether the transmission stays in gear or not. That's more about the transmission parts being worn out, or not.

    There is also a chemical compatibility issue, something about the sulfur in the oil affecting the brass blocking rings.
     
  18. Apr 9, 2016
    BSweet

    BSweet New Member

    Garrett, Indiana
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    I have only put maybe 50 miles on mine since putting in the Napa stuff. I haven't noticed any difference in shifting yet. I seem to grind the shift 2nd to 3rd every now and then. Did it before changing trans oil too. I think it is just my bad habit.
     
  19. Apr 9, 2016
    BSweet

    BSweet New Member

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    If it will hurt something in the trans then I will change it back to a GL4.
     
  20. Apr 9, 2016
    Don X

    Don X The Prodigal Moderator Staff Member 2023 Sponsor

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    Holy smokin' seal. Batman! My local Carquest had Sta-Lube 85W90 GL4 for $11.99 a gallon. :) A little dusty so it's been on the shelf awhile. I don't know if that had anything to do with the price. Carquest are independent retailers under the Carquest brand so YMMV.
     
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