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Manual Transmission Gear Oil - 85 Nissan 720


gryffinwings

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There have been mixed information regarding if it's truly safe for brass. I went down that rabbit hole and there were some responses from the manufacture that claimed it was safe. But really, for $20 you can get GL4 from napa. Sta-lube gl4.

MAN I WAS JUST ABOUT TO ASK ABOUT THE STA LUBE! 26 bucks on amazon. It's gl 4. And a gallon, according to the fsm, will be enough for the transmission and transfer case.
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Transfer case and diff do not require GL4.

I double checked the manual, gl4 for transfer and transmission. Gl5 for diffs. And weirdly enough, dexron for power steering. I have to refill the power steering after I install the new line. Guess I'll return the quart of power steering fluid I bought today
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Transmission and transfer case GL-4

Differentials take GL5.

 

Anything that says GL-5 should not be used in a Datsun transmission.

thanks Mike, I'll get a gallon of stalube GL4 tomorrow.
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Transmission and transfer case GL-4

Differentials take GL5.

 

Anything that says GL-5 should not be used in a Datsun transmission.

 

There are no syncros in the transfer case? Why GL4?

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Now if I can get my clutch unfrozen I'll be thrilled. At least the truck runs now and all the electrical systems work. I'll add tomorrows work on my progress thread in the 720 section

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There are no syncros in the transfer case? Why GL4?

 

It's not just the brass synchros. Differential gears transmit power differently that transmissions and transfer cases. My guess is differential geras transmit force through a 90 degree corner. The gear teeth need more sulphur anti scuff additive protection, about 6%. Transmissions are axial, with the input and output in the same plane less anti scuff protection, about 4%. You might think 2% difference? How is it that different? Well if you think about it 6% is 50% more than 4%.  

 

The sulphur additives form a molecular bond with the steel gear teeth to keep them from steel to steel contact. When GL5 is used on brass it bonds to the copper and forms a super hard layer that cannot be supported by the soft alloy beneath it. The top layer cracks and flakes off and the process repeats slowly eroding the brass rings.  

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So is it not recommended to use a synthetic (Amsoil,etc) in the transmission or diff, due to the possibility of springing a leak? 85 720 5spd 4X4

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IF (the little word with the BIG meaning), if the seals in the transmission, diff, or ? are new a synthetic oil probably won't be any problem. But, if all the seals in the transmission, diff, or ? are  not new, then the synthetic oil will most likely leak.

 

Don

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The rear seal is only $5 and take the primary driveshaft out. The stuff is so thin and slippery it goes where 80w won't.

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Ok. Yeah I know nothing about what the previous owner did to the truck, but I am going to assume nothing, as far as new seals. Was just making sure before I go and buy oils for the transmission, transfer, and diff. So probably stick with a Sta-lube or something similar.

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90w GL-4* trans, trans case and steering box. 90w GL-5** for the differential.

 

* Must be copper or alloy 'yellow metal' compatible

** Do not use in transmission or trans case.

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