:confused: Wondering what type lubrication to use in 89 blazer transfer case. Guy at the auto parts place suggested 20w50,that he had problems when tranny fluid was used,which is what the manual says to use! His is an 87 blazer. Would the blazer year make a diff,or are they relatively the same? Just wondering had my blazer for about a year ,not sure the lastfluid has been changed! Figured i might as well change fluids for my own personal records??:massey:

go by your manual, put ATF (automatic tranny fluid) in it.

The 89 t-case should be a 241 and requires ATF

thanks a much :massey: :smokin:

I was always told that OEM T-cases take 90w if they are cast iron housing and ATF for aluminum housings. The exception was if the case was married to an auto tranny. I had a Turbo 350 married to a NP205 case and they shared fluid.

Hmmm... I've got a NP205 hanging off a TH400 and they don't "share" fluids.

They can't share fluid since a TH tranny and all autos use pressure
to operate.
most of the NP's mated to autos at the factory do use ATF
I agree with the iron case use gear oil and the
alum case use ATF rule if in doubt
but isn't that what a FSM is for

It's probably more accurate to say that chain driven cases use ATF and gear cases use gear oil.
But no kidding on the FSM. At least go down to Pep Boys and pick up a Haynes manual.

what about a 203, it is chain driven. 80w90 there

blazers didn't change body styles til 91 or 2, look for the older case. either way, 208/241, run the ATF