06 tahoe 5.3l 4x4 with g80 code

Discussion in 'Engine & Drivetrain' started by laprodigy001, Oct 5, 2019.

  1. laprodigy001

    laprodigy001 Full Access Member

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    Hello

    I have a 06 tahoe 4x4 5.3l with the g80 code in my glovebox. What fluid can I use for my rear differential? Every fluid I see says ls but from what I gather I can't use that in my truck. Also my rear was rebuilt maybe a year ago. And now it's making a rubbing sound when I turn slow. So I am thinking it's because my fluid is dirty because of the break in after the rebuild. That's why I want to change it.

    Can anybody recommend a fluid that is safe to use in my Eaton g80.

    Thanks in advance
     
  2. tom3

    tom3 TYF Newbie

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    From Eaton's web site:

    What kind of oil should I use? Can I use synthetics? Do I need a friction additive/modifier?

    A: Eaton Posi units perform best when using GL4 (or better) mineral/petroleum based gear oil. A four ounce bottle of friction additive/modifier is also necessary for optimum performance.

    And I would add that the best additive, only one I've found that really works with clutch type differentials, is the actual GM additive.
    Genuine GM Fluid 88900330 Limited Slip Axle Lubricant Additive
     
  3. Scottydoggs

    Scottydoggs Full Access Member

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    g80 is a locker. mechanical at that. pretty sure you just use your normal gear oil. no additives. thats for limited slip diffs.
     
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  4. laprodigy001

    laprodigy001 Full Access Member

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    I thought on the g80 you are not supposed to use a friction modifier.
     
  5. Chris2144

    Chris2144 Full Access Member

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    The g80 uses clutch packs to lock the rear wheels together. This is done mechanically by the diff itself. There has been many questions surrounding this. I have personally used both non additive and with it. If it has truly been rebuilt and the clutch packs have been replaced you probably won't notice a difference between the two. I have put additive in one g80 that was not engaging very well as the clutches were slipping and had positive results. That being said iirc gm says it's not necessary and Eaton says it is. I would contact the shop that rebuilt it and ask what they used in it and replace with that
     
  6. laprodigy001

    laprodigy001 Full Access Member

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    I replaced my gear oil about a week ago with supertech 75w90 full synthetic gear oil. The rubbing/vibration sound/feeling when turning from a stop was gone at first but slowly came back when my wife was driving to work the next day. Could using a cheap gear oil be causing this? Or do I need to add the limited slip additive?
     
  7. SnowDrifter

    SnowDrifter Full Access Member

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    I run good 75w140 in mine with a slight overfill. No additive and it works at it should
     
  8. Rocket Man

    Rocket Man Build It Better

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    I use synthetic in my G80 with no modifier and have for many years with no issues. It’s not a limited slip dif.
     
  9. swathdiver

    swathdiver Full Access Member

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    ACDelco 10-4016 or 88900401
     
  10. laprodigy001

    laprodigy001 Full Access Member

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    Should I get the ac delco gear oil? Or would amsoil be a better choice?
     

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