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Specific Fluid Requirements?


coaz4x4
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I have a '88 WD21 and despite searching etc. cannot seem to get a straight answer...

 

I am trying to change the transmission, transfer case and differential oils.

 

I have heard everything from:

1) I can use 80w90 gear oil in all 3

2) not using a specific oil in the MANUAL transmission can cause parts to fail.

 

Parts stores, forum searching and Google-ing have been unsuccessful.

 

Help please?!

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On colorado4x4.org I've been told that I can use DextronII/III ATF fluid in the t-case and 80w90 in the diffs...

 

But:

"but with the manual tranny there is a SPECIFIC lube you HAVE to USE. if not the syncrononizers in the tranny will explode. i had it happen no kidding. the name of a very common lube is something 90. its not the weight."

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you obviously didn't really read a related threads on this forum then.

 

is your's manual? it kind of seem like it may be but you weren't specific. gl-4 only is the deal with it.. you also need a Liter more then spcified in the owner's manuals and others.

 

diff and tc can take same oil, not sure about the weight.. i'm thinking a little thinner then 80/90 but that should work too.. may be not the best thing for CO winters though... if you have auto trans then use atf if you wish although i think the OM back then said to use gear oil. i switched mine from atf to gl w/o adverse effects.

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87-89's use Dexron III in the t-case. You can switch to gear oil if you want. Like mzxtreme said, I don't think it makes any difference. The 90-95's all use gear oil and the transfer case design didn't change one bit.

 

GL-5 in the differentials. GL-4 in the manual tranny. Redline MT-90 works fine.

 

I'm surprised it was tough to find this out. They list the proper lubes in my Chilton's book.

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"I've been doubting this GL5 recommendation in the Haynes manual somewhat. GL5 will destroy brass synchros and generally isn't to be used in a transmission. I see that MT-90 is a GL4, and GL4 gear lubes do not have the additives that tear up brass components, namely the synchros."

 

See... that is what concerns me...

 

mzextreme- i am still unable to find anything in this forum by searching... at least anything that addresses the specific question of the fluid in this transmission... could you refer me to one specifically, and tell me what terms you used to search for it?

 

So... now to find Redline MT-90 for the trans... and when I fill it I need to get the front up on ramps to "overfill" by as much as possible.

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Being as the fill plug is on the side, I think you'd better tip it to one side instead of just up.

 

Doesn't over filling the transmission cause problems?

 

Is it ok to use Redline D4 ATF for the auto tranny, and Redline 75w90 for the diff?

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