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Fluids in the differentials

Discussion in 'The Garage' started by eshorvath, Sep 8, 2005.

  1. eshorvath

    eshorvath 1/2 ton status

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    I have heard, through somewhere, that in colder climates, ATF in the Differentials is better...doesnt freeze...helps moving gears...better on gas mileage.

    They claim this is also good in the Manual trans.

    Any input for or against using ATF in the Diffs, trans, and TC?

    The only reason id be against it in the transmission, is that it would leak easier than the gear lube, and you would never tell the difference between a trans leak and a TC leak.

    But right now, I do not even know if i have a trans leak or an engine leak, as it dripd on the bell housing...sigh.

    Eddie
     
  2. MTMike

    MTMike 1/2 ton status

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    I've never heard of using it in the diffs, but I know for sure that the manual transmissions in both my old V6 Camaro with a T5 and my 99 Z28 with a T56 call for ATF as their fluid.

    Mike
     
  3. eshorvath

    eshorvath 1/2 ton status

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    i believe that the book on this calls for 80/90 for the trans, if im not mistaken.
     
  4. sandawgk5

    sandawgk5 3/4 ton status

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    My dad had a 1993 S-10 and it called for ATF in the manual box.

    Ira
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    At what temp does 80-90 cause problems? I know GM spec'd block heaters for some climates, but I can't recall any diff heaters. :)
     
  6. eshorvath

    eshorvath 1/2 ton status

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    I know when I moved to Alaska, they told me to put ATF into my differential of the 93 S10. They said gear lube would freeze.
    Im wondering if since it is freezing here in the winter, (im by crater lake, oregon), if I should try it this winter too, maybe it will help with the mileage in the winter? MAybe the gear lube freezing caused my differentials to shatter a couple years ago...
    Hmmm.
    Eddie
     
  7. eshorvath

    eshorvath 1/2 ton status

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    Would ATF in my differentials HURT the differentials in the hotter, summer weather?
    Maybe this is a better question.
    Eddie
     
  8. HarryH3

    HarryH3 1 ton status Author

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    The ring and pinion are hypoid gears, which have a "wiping" action of the gear teeth against each other as the pinion drives the ring gear. This creates extreme pressure that most lubricants can not deal with. ATF is not designed for hypoid gear use.

    A good synthetic gear lube, which is designed for hypoid gears, will work fine at the temps that most sane humans want to be out and about in. :wink1:

    Unless you're driving in Alaskan winters, you shouldn't have to worry about it.
     
  9. MTMike

    MTMike 1/2 ton status

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    Yeah, I agree. You shouldn't have to worry about it. We have some pretty harsh winters (-20 - -30 at times) here and I've never heard of diff oil freezing or needing ATF to keep things running better in cold weather.

    Mike
     
  10. atho

    atho 1/2 ton status

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    I have noticed in my truck with SM465 and 90w gear oil, the shifts are a little harder when the truck is cold. In -20* weather, that is. But they're fine when it warms up.
    Never heard of ATF in diff's.
     
  11. HarryH3

    HarryH3 1 ton status Author

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    Synthetic gear oil can solve that for you. It doesn't thicken up nearly as much as dino oil in the cold. :cool1:
     
  12. bobdahawg

    bobdahawg Newbie

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    atf and diff,s

    most peeps that cut and turn diff's add atf to the oil as you have to overfill the diff to keep the pinion lubed the atf is a anti foam agent in that case as it reduce's the surface tension of the gear lube. and my thinkin it would be a benifit in cold weather. bout a cup is all you need. have fun
     
  13. JonV

    JonV Registered Member

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    What does the owners manual say???? Good idea to always start there. Mine on my 79 Jimmy says SAE 80W-90 GL-5.Colder climates SAE 80W GL-5. These will work fine in Oregon.

    Some circle track racers, and some drag racers I've heard of use ATF. Primarily because of the low viscosity they figure it reduces friction and they pick up some H.P. Remember, that is for a short time period and they have lots of money and don't care if they have to replace the gears, etc. You want to use a GL-5 gear lube. The right lube for the right application.
     
  14. JonV

    JonV Registered Member

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    OEM spec is 80W or 80W-90 both GL-5. In Canada 80W. 90W bit to thick for your climate. Has to heat up in order to shift, hard shifts caused by increased viscosity, thicker and syncros don't line up.
     
  15. JonV

    JonV Registered Member

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    P.S. If you have a limited slip / posi in the rear end, don't forget to add the correct amount of friction modifier ( limited slip additive) when changing the gear oil.
     

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