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What oil do you run in your t-case np205

Discussion in 'The Garage' started by primerk5, Mar 16, 2007.

  1. primerk5

    primerk5 1/2 ton status

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    I normally run 90 wt, (gear oil) Though a friend says to run Trans fluid. I'm thinking gear oil is what should be in the t-case.
     
  2. sgarrison

    sgarrison 1/2 ton status

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    If its a cast iron case, like the 205, run gear lube. If its an aluminum case then trans.fluid should be run.
     
  3. 73k5blazer

    73k5blazer Unplug the matrix cable from the back of your head Premium Member

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    NP205 takes 80w90, period.

    I run Sythentic 80w90 Mobil 1 in mine.
     
  4. primerk5

    primerk5 1/2 ton status

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    Cool, Gear lube it is! Thanks
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    "Run trans fluid" comes from the fact that later on that's exactly what GM did. (My '91 205 came that way)

    Makes it a bit less of a problem if the seals fail on an auto trans application, since the fluid won't be contaminated, but other than that, it's pointless to run ATF.
     
  6. mrdrinksalil

    mrdrinksalil 1/2 ton status

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    I have a NP205 and a TH400. I thought the 205's behind autos should have trans fluid... I dont' think there are any seals between the tranny and the transfer to keep the fluids seperate. Now I'm confused...
     
  7. 8_YOUR_H2

    8_YOUR_H2 1/2 ton status

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    I run ATF in the t cases. I would say 1/2 of the cases I have had in the past were oil and the other half ATF.
     
  8. 454k30

    454k30 1/2 ton status GMOTM Winner

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    I cant speak for the autos but my sm465 has a seal in the adapter to prevent its fluid from getting into it. The t-case side doesnt though. My truck is an '83 and came with the 465/205 setup. The factory manual says to use ATF in the case. I use synthetic 80-90w.
     

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