I am planning to change my rear differential oil in my 07 M35 and was wondering what kind of oil to use. I was considering using Mobil 1 Syn 75W-90. Is this the best stuff to use? Do I need to add LS additive or not? Also, are there any crush washers I need to change on the plugs? Thanks.

Mobil 1 75W-90 synthetic gear oil (or Mobil 1 75W-140 synthetic gear oil) is perfect for the differential. No additive needed.

Z

I've used 75w-90 Mobil 1 oil on my rear diff of my FX35. I am planning to do the same on my M. You need to buy 2 quarts since you will use just a tad more than 1.5 quarts.

Appreciate it.

zerg711 wrote:I've used 75w-90 Mobil 1 oil on my rear diff of my FX35. I am planning to do the same on my M. You need to buy 2 quarts since you will use just a tad more than 1.5 quarts.

Spot on and get a pump to pump from the bottle into housing. Cost $5 at auto parts store and you will always have it! 1.6 quarts!!!

Simple and a good thing to do!

zerg711 wrote:I've used 75w-90 Mobil 1 oil on my rear diff of my FX35. I am planning to do the same on my M. You need to buy 2 quarts since you will use just a tad more than 1.5 quarts.

And, if you have the X model, you need to double that amount - there are two differentials.

Z

A pump will definitely help. But remember, make sure you can remove the filler plug first before attempting to remove the drain plug. You need a 10mm hex for removal and a breaker bar may help (especially in my case with tendinitis).

Nissan 75W90 synthetic oil is recommended by the Infiniti manual for the rear diff for my 2009 g37SX. It is very expensive. When the Infiniti dealer did the 30,000 serviced they used regular 80W90 oil. Can I make them use the recommended oil at no extra labor charge? Thanks

scotg37 wrote: ↑

Thu May 12, 2022 11:21 am

Nissan 75W90 synthetic oil is recommended by the Infiniti manual for the rear diff for my 2009 g37SX. It is very expensive. When the Infiniti dealer did the 30,000 serviced they used regular 80W90 oil. Can I make them use the recommended oil at no extra labor charge? Thanks

I can't imagine why they'd want extra labor for a different oil, but I'm sure they'll up-charge you for the genuine article. You can always supply your own and just pay them the labor.

PS - The FSM says any 80W90 API GL-5 hypoid is fine, or straight 90W for hot climates. See page MA-9:
https://www.nicoclub.com/service-manual ... 9%2FMA.pdf

Is the official Nissan 75W90 diff oil already mixed with limited-slip friction modifiers? That could be a reason it is specifically so expensive.
I believe the 2009 G37 actually has viscous limited-slip diffs in them though, so you probably want those modifiers and completely standard oil wouldn't be the best for them.

I have personally used RedLine 75W90 diff oil in both my older G37 VLSD I had on my M, as well as with my newer helical gear LSD. It costs about $45 for the oil to do an oil change, but I only have 1 diff since I am not AWD. Double that cost with an AWD car.
Note that the RedLine 75W90 diff oil has additives and friction modifier already mixed into it. I use it because Z1 said it was fine for me to do so, even though Wavetrac says friction modifier diff oils arent the best to be used with helical diffs. I haven't had any issues though in the many years I have had this diff and used that oil though.

Should the washer and but be replaced or just reuse the old one?

I believe it is a copper crush washer correct? If so, it should be replaced.

I've replaced front and back with Amsoil three times...no friction modifiers needed. I'd replace the bolt and use anti seize-had some trouble with one and had to have it professionally removed. 180,000 miles on my 2007 M35x.

Sacto Infiniti wrote: ↑

Tue May 31, 2022 5:37 pm

I've replaced front and back with Amsoil three times...no friction modifiers needed. I'd replace the bolt and use anti seize-had some trouble with one and had to have it professionally removed. 180,000 miles on my 2007 M35x.

Yes, the friction modifiers were only mentioned for scotg37's question on oil. His G37SX has different differentials than the M's do. The G37 sport's came standard with viscous limited slip differentials. I believe later model year M's with sport package also did but I am not 100% sure on that. The 2006-2007 M sports definitely did not though. As far as I am aware, no AWD models of these years came with a VLSD though, all open diffs and slips was controlled electronically by the computer by modulating the brakes a bit.

Which brings up an interesting question, Does a G37SX have a VLSD or an open diff? The sport part says the VLSD should come standard, but the AWD part only has open diff options. So which did Nissan use in his oddball model car? If it is an open diff, no friction modifiers are needed and they will do nothing at all. The friction modifiers are only supposed to be there for clutch type (like the new 2023 Nissan Z performance model) and viscous type differentials