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NP 205 Lubricant Question

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by k5bushhog, Apr 26, 2002.

  1. k5bushhog

    k5bushhog Registered Member

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    What is the recommended lubricant for the NP 205 transfer case.......Thanks
     
  2. Triaged

    Triaged 1/2 ton status

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    This is one of those questions that should have a simple answer...When our trucks were made GM said to use 80w90 gear oil. Later they said to use ATF. Some people put engine oil in them to get better gas mileage (and to keep it working in COLD climates). My sugestion...put something besides mud in it and it will last almost forever.
     
  3. mkmiller

    mkmiller 1/2 ton status

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    LOL! GREAT ANSWER! LOL!
     
  4. k5bushhog

    k5bushhog Registered Member

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    Thanks for the reply Triaged. I bought the truck and it had atf in it. I had heard that the 80-90 was the recommended stuff....Thanks very much.
     
  5. 70~K5

    70~K5 1/2 ton status

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    I think you'll find trucks with a manual trans tend to run gear oil in the NP205. Trucks with autos tend to run ATF in their NP205. That way if the seal between the trans and TC leaks you won't cross contaminate the lube in either.
     
  6. Triaged

    Triaged 1/2 ton status

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    Actually my 205 has a mix of ATF and gear oil for that same reason. No gear oil has mixed into the trans that I can tell.
     
  7. ntaj*ep

    ntaj*ep 1/2 ton status

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    I run 80w-90 weight gear oil in mine. However there is an o-ring on the end of your adapter that will leak atf into your t-case. It will eventually over fill and your seals will start to leak. I would make sure that o-ring is ok, then filler up wit some fluid. Better to have too much than not enough. LOL
     
  8. LKJR

    LKJR 1/2 ton status

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    Just stuff it full of KY, if it ever breaks just complain to the company, maybe you could win some kind of lawsuit or something for it not lubbing good enough. But then again it's water based, too much like mud
     
  9. 79Beast

    79Beast 1/2 ton status

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    I recommend Coastal 80-W90. I buy mine in a five gallon bucket at Autozone. It is cheaper than buying gallons or quarts plus it is GL5 (limited slip rated) rather than GL4. The GM service manual reccommended 90 weight for my 79 and for the 74 that my tcase came from.
     
  10. Steve_Chin

    Steve_Chin 1/2 ton status

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    I used to use generic 80W-90 GL4/GL5 EP lubricant and that worked fine. I'm running Red Line synthetic MTL in there now.
     
  11. 1bad82k5

    1bad82k5 1/2 ton status

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    I just use straight 80-90. I would switch to synthetic, but mine leaks like a sieve so i just run conventional.
    eric
     

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