Ok so I have looked high and low on the forums and I can't find info anywhere. I'm about to change my trans n diff fluids. The last time I changed them I used RP 75w90 in both the diff n the trans b/c it covers both GL4 and GL5 requirements. Well now I'm due for it again. I'm gonna use the RP for the rear but I got a good price on Mobil 1 75w90 that I was planning on using for the rear. Has anyone used this oil n if so what are your thoughts on it? How does it shift? Please don't tell me to use Amsoil, Motul, Redline b/c I'm currently in broke status n this jus happens to fit my budget. Any help and input would be appreciated. Thnx

 

I meant to say that I am planning on using the Mobil 1 for the trans!

 

You want to use 75w85 for your transmission.

 

Do not use the Mobil 1 in your gearbox, although it's fine in the rear axle. If you can't afford a good synth right now (e.g. Redline MTL), just use a non-synth of the proper spec and you'll be fine. Synthetics are great, but you can do just as well with dino oil if it meets specs and you change it at the required intervals.

 

OEM is the best for the transmission. It's like $12 a qt.

Royal Purple is GL5, so your synchros probably hate you for using it in the trans.

 

But Mobil 1 is GL-4, isn't that what our gear boxes use? Y is it that u can use Motul synthetic or Redline or any other in the gearbox but not Mobil 1?

 

For one, the viscosity of the Mobil 1 75w/90 is too thick for the gearbox. The bigger issue is that it's fine in LSD diffs because its an EP (extreme pressure) oil with friction modifiers, which won't play well with your gearbox's synchros. It's actually too slippery. Finally, I've got a few bottles of the Mobil 1 75w/90, which I use in the rears of my Alfa Spider's, and they're only labeled API GL-5. I don't see any mention of GL-4 compatibility anywhere on the label.

 

There's a sticky at the top of this forum...

https://my350z.com/forum/maintenance...intenance.html

that contains a link to the huge threads on transmission and diff changes...


https://my350z.com/forum/engine-driv...ssion-oil.html

https://my350z.com/forum/engine-driv...-easy-way.html

https://my350z.com/forum/engine-driv...ion-flush.html

that contain all kinds of suggestions for fluid mixes.

 

Yea I saw that earlier n returned the oil, I prolly picked something else up thinking it was Mobil 1, I ended up biting the bullet n getting the RP Maxgear 75w90, its been good to me so if it ain't broke don't fix it.

 

Believe me I'm not the noob who don't search, this ain't the 1st forum I've ever been on. I looked, jus didn't get the answer I was looking for. Found plenty of suggestions for fluids but nothing for what I wanted. Thanx for the links tho.

 

I just changed my MT and LSD last weekend.

Nissan MTF from Courtesy Nissan $10 per qt.
Castrol Syntec Synthetic 75W-90 from O'Reilly. $10 per qt.

Good luck.