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Wrong oil = Transfer case damage???

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Smitty, Sep 10, 2000.

  1. Smitty

    Smitty 1/2 ton status

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    Just checked the fluid in my 208 and it looked like a mixture of 90wt and ATF. I've drained it and refilled with ATF but started thinking about what might best for my situation. Is there any advantage/disadvantage to running ATF instead of a heavier gear oil? I've looked over some of the previous posts and can buy the line about going to ATF for fuel savings. Are there other reasons? It seems like a heavier oil would have a higher sheer rating and would work better under a load.
     
  2. stephan van leir

    stephan van leir 1/2 ton status

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    You need to run ATF in your 208. The 208 has an oil pump that requires the thin fluid.
     
  3. Smitty

    Smitty 1/2 ton status

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    No that's a twist that I hadn't thought about. Still don't have a comfortable feeling with ATF in there but I'm not going to put that big dent in the wallet just to test it. Thanks for the info.
     
  4. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Don't worry, man. I've owned my Blazer for over 8 years, have always run ATF in it, and have never had a problem........It IS the recommended lube for a 208, anyways.
     
  5. Thunder

    Thunder 3/4 ton status

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    Your T case should not be hurt. The main reason they run ATF instead of 90 wt in them is. That if they are married up to a automatic trans and you loose the rear trans seal. 90 wt oil will not get in the trans.90 wt gear oil will ruin an auto trans. Do not use 90 wt if the T case is bolted up to an auto tranny. Use ATF.
     
  6. jarheadk5

    jarheadk5 1/2 ton status

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    Hey Smitty, I know you've already drained the mixed oil and refilled, but you really should do it again, after driving in 4HI for a little while. This will ensure that all the gear oil is flushed out to avoid any problems down the road. If nothing else, it'll give you an excuse to go wheeling!!

    [​IMG] Semper Maintenance!
     
  7. 6.2Blazer

    6.2Blazer 1/2 ton status

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    The 208 transfer case, and most of the newer transfer cases in general, are designed to run ATF fluid. You will gain absolutely no extra protection by running heavier fluid, and more than likely running something like 90 weight will greatly shorten the life. The reason is that the newer transfer cases and transmissions are being built with closer tolerances which don't require the heavy fluid to properly lubricate and allows ATF to be used for smoother operation, and less drag which equals better mileage.
     

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