It's time to do the front/rear diff service and the transfer case. The car has about 75K miles on it now and it has not been done yet. For some reason my Infiniti dealership doesn't know the correct fluid weight they say their system only goes back to 2010? Is it okay to use Mobil 1 Full Synthetic 75W90 in the front and rear diff? I've read some places on here it calls for 80W90? Also what does everyone recommend for the transfer case? Nissan ATV transmission fluid? They told me 1.3 quarts for transfer case and 0.65L for front diff and 1.4L for rear diff. Any help is appreciated! Thanks!

 

I put 75/140 Valvoline synthetic, in ALL my OPEN diffs, and yes I am in Minn. where it gets fairly cold for a few months, I never had any issue with this oil! Your X has fewer miles than mine, (87,000) on a car almost 16 years old. I believe you are right on the transfer case, (which IMO almost no one changes) I did this like 5 years ago and can't remember what I even put in, but it was NOT the Nissan Matic S that goes in the 5 or 7speed tranny. The front diff is pretty small, the rear diff is average size, and it sounds about right on the transfer case capacity.

 

I think I actually sourced Matic D or J for the TC... can't remember now.. it's been a number of years. It doesn't take much fluid

 

V36 chassis specs from the FSM

Front and rear diff, GL-5, 80w-90

Transfer case is actually Matic-D (the stuff they use in the CVT transmission). iirc they're actually the same friction coefficient but that was the old fluid that was used on the previous generation transmissions. Newer transmissions were engineered around the fluid but it was switched to synthetic for a longer fluid change interval. TECHNICALLY it should be fine to use Matic J/S in the transfer case.

For example, the old 1990's Nissans all used Matic D transmission fluid.

When Matic J first came out it was INCREDIBLY common for people to have dealerships use it in their Matic D transmissions and it wasn't an issue.