I'm about to change my diff oil for both front and rear but local auto shops around me have Mobil 1 75W-90 everywhere. Like 12 bucks a quart. Hard to find 80W-90 (according to the manual) around me for my car 13' G37x. I also saw the RP 75W-90 one $22 bucks a quart. Is it really better than Mobile 1?

 

Its fine. Stay away from rp gimmick

 

Used that gear oil myself as well, no issues at all.

 

Mobil 1 is fine, as is 75W-90. I'm running Redline in the rear right now (still need to do the front) which can be found on amazon for $16.

 

I recently changed my front and rear differential oil on my 2012 G37xS coupe. I also used 75w90 gear oil. No problem at all and car rides more smooth than before.

While you are at it, why not change out your transfer case oil as well? Make sure to use the right fluid. For my 2012 G37xS, it uses Matic J for transfer case.

 

I went to the Nissan Dealer and to my surprise, they sell Mobil 1 75w90. You can get it as low as 10 a quart.

 

Oh, The manual also stated use that Matic J for my car, but does it really has to be Matic J for transfer case? It cannot take Mobile 1 ATF? Hard to find Matic J. Did you know how much quarts you need for transfer case? You just fill the transfer case until it dripping out the fill hole right?

What. Interesting.

 

For transfer case I decided to stick with Matic J and this was based on what others have said in the past and recommended to me.

Yes, you just fill it until it starts to overflow from the fill plugs (differentials and transfer case).

Something that I did, but you don't have to. For both the differentials and transfer case, I pumped about 3-4 pumps of new fluid with the drain plug still off so that I can wash out any residual old oil. After the new fluid is completely drained, I closed the drain plug and pump new fluids in until it overflowed. Then torque everything spec.

 

Thanks for the tip. Did you remember how much quarts you bought for the Matic J? I may call Infiniti or Nissan dealers around or somewhere cheaper like Amazon. That Matic J seems to be expensive. What the torque spec on those plugs? 25 ft/lb?

 

I bought 3 qts of Matic J for just in case I spill some by accident or in case of leaky drain plug, but used about 1.5 qts only.

For my 2012 G37xS coupe, the differentials and transfer case were all torqued to 26 ft-lb based on FSM.