I know that the manual is very specific about using Matic-J or Matic-S for the transmission, due to other fluids causing driveability and durability issues. But how specific is the fluid the manual recommends for the front and rear differentials? Is the Hypoid Super GL-5 80W-90 really needed? Or can I run Amsoil or Royal Purple 80W-90 without issue?

 

Also, I can't find anything about the need of a limited slip friction modifier. Does it need it?

 

 

Any name-brand GL-5 gear oil should meet Nissan's requirements - Valvoline, Lucas, Mobil 1, store brands, and so on. You can use gear oil with or without LSD additives. Just picking Valvoline for an example, as it's extremely common and available in just about every auto parts stores, Walmart type stores, and home improvement stores, their basic "High Performance Gear Oil" meets the GL-5 spec. The 75W-90 grade also happens to include LSD additives. Regarding 75W-90, Nissan apparently changed the spec from 80W-90 to 75W-90 and the differential(s) didn't seem to change. Many here have indicated using 75W-90 with success as well.

If I'm not mistaken, only the Sport model has a limited-slip differential. In that model, you must use gear oil with LSD additives.

 

Thanks for the info, makes it a little easier.

I figured this was the case, hopefully someone can chime in with certainty, if not, it's not big deal to add the friction modifier.

 

Don't add anything, just get gear oil that has it already blended in. Lucas 80W-90 heavy-duty gear oil has it included, Mobil 1 synthetic does as well

 

You only use friction additives on clutch-style LSD, the OEM unit in the G35 is a VLSD which is a sealed unit that has it's own super gooey fluid inside that never gets changed EVER. Just stick to the correct viscosity of fluid and you'll be fine. Gear oil is something that you don't really need to stick to the Nissan brand stuff either, that's more for the automatic transmissions.

 

Yep, I knew this, I just wasn't familiar with what type of diffs these things had.

 

This was where I was clueless, didn't know if maybe Nissan had some special stuff to use. Until I got my G, I had never dealt with specific trans fluid at that level. ATF+4, sure, but hadn't seen brand specific before.

 

There's a lot of overall quality differences when comparing various brands and for the most part you get what you pay for. Better gear oil typically lasts longer before breaking down. For a normally driven street car that follows the 20k mile interval on differential gear oil it really doesn't matter though. If you drive the car hard or if it sees the track a couple times a month then you can really benefit by using a high end oil like Redline or Lucas because they will last just a bit longer under those conditions. Normal conditions though these differentials don't get that hot, I've only ever seen 130F on mine for regular street/highway use on the hottest of summer days. You can be almost 200F on a really hot track day if you're doing a lot of laps on a clutch-style LSD, that's where a finned diff cover helps a ton, better heat dissipation as well as the increased fluid volume.