NP231 Transfer Case, AX-15, 75W-90, and Dexron II
 

I'm going to change the fluid in my tranny and transfer case soon. The FSM calls for 2.2 pints of Dexron II for the TC and 6.75 pints of 75W-90 for the transmission. Can I use Dexron 3 or higher with no ill effects? Also, should I use the $5/qt. gear oil or go with the Mobil 1 synthetic? The jeep is my daily driver and goes 450 miles nonstop 8 times per year.
:icon_rolleyes:

Rob

Use dex 2 or 3 or 4... I'd use gear oil in the rear end with changes at proper intervals. Personally I would NOT switch to Synthetic in an older high mileage vehicle, more potential for issue than real benifts.

Does not really matter what ATF you use in the transfercase. Your choice if you want to run synthetic gear oil, it may help keep the transmission a little cooler, but I've never had a problem with plain ol' 75w90 gear oil.

Thanks for the quick replies. Local auto shop will do both for me for less than fifty bucks!