tcase lube

so i was reading the manual for some reason today and it says ATF but iv been running 80-90W gear oil in there for some time now with no problems so far , sound i be worryed an swap it back to atf or should i leave it ? what have you guys been running?

The recommended lub is usually the best. Though I have a tendancy to replace it more often than the service schedule recommends.
Gear lub (GL 5) has some fairly serious detergent components (sulfur). No telling if the gear lub detergents and your internals are compatable.
The oil pump in your transfer likely has some problems moving the gear lub as quickly or efficiently as the ATF.

thumpin_xj said:

so i was reading the manual for some reason today and it says ATF but iv been running 80-90W gear oil in there for some time now with no problems so far , sound i be worryed an swap it back to atf or should i leave it ? what have you guys been running?

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You should pull the case, clean it, reassemble, and use ATF. The oil pump has probably not been moving any oil since you filled with 80 weight.
If you don't change it back to ATF, please let us know how long the tcase bearings last on 80/90. I'd be interested to know.

Change it back, once it gets real cold the 80-90 is way to thick and stiff.

If you don't change it back to ATF, please let us know how long the tcase bearings last on 80/90. I'd be interested to know.

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over 2 years so far , probly because it doesnt get that cold here in BC will it be ok to just drain it fill it with ATF then just drain an re fill it in a few days ?

I think the best thing to do would be to take it apart and spray the holy hell out of it with Berryman's B-12. Get all the residue off, possibly change out that oil pump (give it a hard look), put it together, and run it with Dexron III ATF. I'd run it no more than a week and change the fluid again.

Yea 80/90 is so much thicker than the ATF, And ATF is like hydraulic oil not just grease, It might be doing something other than just lubing the gears in the case (i dont really know though)

w/e ist been in there for over 2 years ill just continue the plan of runnign it till it breaks then d300

thumpin_xj said:

w/e ist been in there for over 2 years ill just continue the plan of runnign it till it breaks then d300

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I've had ATF in a NP 231 for pretty near 20 years (yearly ATF changes). Transfer still works well, have replaced a couple of seals over the years.
If I remember correctly it took about 3-4 years for the damage to become apparent (sinc rings and hard shifts) on my AX 15 when I replaced the OEM GL 3 with the wrong stuff. GL 5 was incompatable with the sinc rings.
Front bearings got noisey in the 4 speed tranny in my Dodge pick up a few years after switching to GL from the OEM ATF. GL was actually listed as an alternaitve lubricant in the service manual, but I have my suspicions the bearings didn't oil as well, with the thicker stuff.
ATF (Dexron) is cheap, there is really no advantage to running GL, other than it may quiet the transfer down some, for awhile.
If you have the 242, I'd be more concerned. In part time, it has some built in slippage, GL make make it slip in ways that cause excess wear.

thumpin_xj said:

w/e ist been in there for over 2 years ill just continue the plan of runnign it till it breaks then d300

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then why did you ask?? :twak:

You do know that D300 has the front output on the wrong side, right? Do you plan on changing the front axle too, and maybe a custom drive shaft? It is so easy to change the fluid twice with Dexron III ATF, then call it good.