Transfer case lube

My cooling system is working fine now. I'm back with another question.
When ever I park my 99 envoy with the nose slightly lower than the back end the "Service 4 wheel drive" light lights up. I'm almost sure(although I
havn't checked it yet) the fluid level in the transfer case is low. My question is, What kind of fluid goes in it? 90 weight gear lube? or something else?
Dave
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Two words: Owners manual.
If you don't have one, pretty sure your Envoy uses Autotrac fluid in the transfer case. Available only at GM dealers.
Doc

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Thanks Doc
Manual says "Automatic Transfer Case Fluid" (GM part number12378396) I guess If I had paid more attention to what I was reading I would have noticed that it doesn't say "Or Equivalent"
Dave
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Willywanka wrote:

The fluid is called Autotrak, and it is special and specific. By the way, the "service 4 wheel drive" light will have nothing to do with the fluid level as it does not monitor that. You would need to get the ATC (automatic transfer case) scanned for codes to see what is really going on.
Ian
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can scan from the access port.
Dave
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the proper lube is a blue color called auto-trac fluid, the t-case was originally filled with atf but GM had a bullitin in 2000 to only use auto-trac fluid. but I dont think it will fix your problem. there is no level sensor in the t-case. goog luck. moo
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