1970 Z28 4 speed fluid question

Discussion in 'Transmission & Driveline Topics' started by VoodooChildZ28, Jul 9, 2020.

  1. VoodooChildZ28

    VoodooChildZ28 1970 Z28

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    Hello going to replace all fluids when new radiator/electric fan kit arrive what would be appropriate fluid for the Muncie and if you want to save me some more time what gear oil for the posi ? Looks like it’s leaking so I want to replace the gasket and fluid. I’m a Royal Purple fan but open to any good brands Amsoil, Lucas etc. thanks all God bless
     

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  2. checkmate201

    checkmate201 1970 SS 350 4sp 06 C

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  3. Lowend

    Lowend Administrator. .a car, a man, a maraca. Staff Member Lifetime Gold Member

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  4. VoodooChildZ28

    VoodooChildZ28 1970 Z28

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    Thank you gentlemen. What about for the posi?
     
  5. Lowend

    Lowend Administrator. .a car, a man, a maraca. Staff Member Lifetime Gold Member

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  6. VoodooChildZ28

    VoodooChildZ28 1970 Z28

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    Fantastic advice thank you. Summit has it. Now for the Muncie what’s the captacity and of the posi? Thanks I’m advance
     
  7. COPO

    COPO Veteran Member Lifetime Gold Member

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    Forget about capacity. Get 2 bottles for each the trans and posi and you’ll have some leftover. Fill both cold to the below the threads so when you stick your pinky finger in the hole, you get fluid on the tip of your finger.
    Check when hot and fill to the bottom of the threads or when it starts to spill out of the fill hole. For both I use non synthetic GM 80w90 gear oil and with the posi I add 1 bottle of GM posi additive.
     
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  8. Gary S

    Gary S Administrator Lifetime Gold Member

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    I use Amsoil MTG in al my manual trannys. It makes the shifts smoother than you ever dreamed they could be. I have an old '81 Chevy pickup with the Muncie truck 4 speed. They shift like a pig new and don't improve with age. This one from new was very difficult to get out of 2nd and to 3rd. After suffering with it for 20 years, I switched the lube to Amsoil MTG. It now shifts like butter with no more of that hangup in 2nd. That convinced me to put the same stuff into my Camaro Muncie. The Camaro always shifted nice, and with Amsoil, it might be even a bit better.
    Amsoil MTG is specially formulated for old Manual trannys. It is GL4 rated for trannys.
     
  9. VoodooChildZ28

    VoodooChildZ28 1970 Z28

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    Thank you boys. This bastard does not want to get into 3rd gear and praying the new trans fluid helps, as well as a gasket fixes the posi leak. I almost bought 4 quarts trans and 2 posi so thanks for the help! I’ll get two of each and pray this cranky tranny will find 3rd haha as well as stop the small leak
     
  10. COPO

    COPO Veteran Member Lifetime Gold Member

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    The additive should only be this size.
    [​IMG]

    If it won’t go into a gear then do a neutral alignment on the shifter.
    [​IMG]

    Gauge pin
    [​IMG]

    [​IMG]
     
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