Just occured to me I'll be needing to fill up this 4WD Dual Range I'm installing. Wondering what weight I should be using. What reminded me of this was the fact my 2WD 5speed I pulled out recently leaked ALL of it's gear oil on my garage floor... where'd I put that kitty litter?

 

Thx

80W90 gear oil is the factory spec and seems good on the synchros.

80W90 gear oil is the factory spec and seems good on the synchros.

Word, thx

My 88 owners manual says 80W90 - straight 90 depending on climate conditions.. I'll get the exact ranges in just a little while.

Oh another thing my friend reminded me. Gotta fill up the rear diff! What should I be putting in that? Also how do I fill it up all the way w/o making a huge mess?

 

Thx

you buy a gallon bottle-with the fluid of your choice-and a cheap pump that has a hose to fill the REAR first, then fill the front

complete change of fluid takes less than a gallon, check for accuracy

Fill the rear diff to the top of the hole. You don't need a pump. Just a funnel, and a peice of tubing will work fine. Use cheap 80w90 in your diff, and Redline gear oil in your tranny. Will save the syncro's.

 

GD

Welp I picked up a gallon of Valvoline SAE 80W90 on my lunch break

 

Thx for the replies guys.

i just checked my Owners manual(1988) and it says to use 80W90 if you experience subzeo temps, 90 otherwise..

 

But given your location, you probably get cold enough to justify the 80W90.

Phew.

 

I am so used to the Northern "factory spec" that I don't even know about using different anywhere else. Ill have to be more careful of that. Good thing MorganM lives even further north than I do.

Phew.

 

I am so used to the Northern "factory spec" that I don't even know about using different anywhere else. Ill have to be more careful of that. Good thing MorganM lives even further north than I do.

haha yeah its funny when you are reading the owners manual and it describes "Extreeme Condtions" and you are like 'um thats a typical winter commute...'

For my climate (New Mexico) 75W90 seems to be a recommended oil. I'm planning on putting in Redline 75W90 because of it's ability to help synchro woes as well.

Question is - can you even still buy straight 90W? All I have on the shelf is multigrade (75w90, 80w90, 75w140, 85w140, and straight 140w). 80w90 should be fine for all - acts like 80W when cold and 90W when hot.

I've had really good luck with Quaker State 75w-90 synthetic gear oil, which I changed to in both the tranny and rear diff last summer. After at least 10,000 miles it's still as clear as the day is went in, the synchros seems to be in better shape, and it shifts much easier when it's cold outside. I don't know if this is a common problem with synthetic gear oil like it is with engine oil, but it hasn't leaked a drop yet either.

 

Only disadvantage is the price, but since the drain interval is about three times as long as with dino oil, it's really about the same anyway.