I'm due for a differential and power steering fluid drain/refill. Now that the car is no longer under warranty i'd like to do this myself.

I've checked the FSM, the PS fluid is just like every other Nissan i've had in the past -- ATF, so that's no biggie.

But for the Differential, i can't find the genuine Nissan stuff. Which one do you guys use? I'm not educated well-enough with differentials to know if a GL-5 equivalent (75 or 80w-90) is good enough without added additives.

I've read on some other Nissan forums that some oils cause differential chatter. I'm leaning towards readily available Mobile 1 stuff. However, some say that Mobil 1's "LS" series oil has additives that don't bode well for our type of LSD's.

Any help is gladly appreciated.

Thanks.

p.s. On a slightly different note, i'd rather not do another AT flush. Will the more commonly done drain/refill 4qts at a time, over a couple hundred miles, work just fine?

 

i have been doing a lot of research on this as well since im due for a change as well, i found that the only genuine nissan diff gear oil available is their GL5 75W145 which most dealers say is a good swap for the recommended 80w90 and offers more protection, however i feel for our cars its too thick at higher temps and should add drag and in turn reduce mpg and a bit of power IMO.

As for the LSD we should not need to add any additives since we dont have clutch style LSD and is in fact a fluid based packed LSD within the main diff so no fluid you add in the main diff gets to be in contact with the LSD(which is the reason you need to get a new diff once they fail), so adding any additives should have no +/- effects on the diff imo.

Im looking into getting an AM syn 80w90(RP or M1) which i believe is a perfect suit for our cars. Nissan does however offer 75w90 MTF online which i will be getting for my tranny but would rather stick with a thicker 80w in the rear diff which sees more abuse and high temps imo.

Keep me posted as well on what route you end up taking, im planning on doing this next week.

EDIT: the drain and fill is fine for the ATF, if you want to clean up more you can do that without a flush by using the little pipe that carries the ATF to the radiator cooler which is a recommended way of atf swap per the service manual. It recommends having another person pour in new atf from up top while the car is running and the hose is disconnected and pumping out old ATF into a bucket, and then you stop when you start seeing new fluid come out. check out the FSM.

hope this helps a bit

 

Excellent response! Very informative. Thank you, as always.

I called the dealership and they can't give me an exact answer as to what they used on my car when it was machine flushed at 30k. I guess it's like engine oil, they use whatever they can get in bulk for a good price at any given time.

That said, i went ahead and got 2 qts. of M1 75w90 LS oil. There were several brands on Autozone's shelves, but they had a sale on the M1 (incidentally) so i got them - came out to about $7 a quart.

On the ATF, the FSM isn't very clear. I read it as two separate entries, a regular drain and fill and, if you want to completely replace the fluid, the removal of that pipe to the radiator then performing it as you mentioned.

As i don't have anyone to help me with this, i might just go ahead and do the 4-5qt drain/fill, then again a couple hundred miles later. If i do this every 30k, it should be just as good as a full drain/refill every 60k, no?

Thanks again!

 

No problem, this is nothing compared to the help you have provided me

Anyways the 4-5qt drain/fill and then redo after few hundred miles should do the trick nicely since there is a total of 10qts in the tranny, the first change should help the old fluid mix in and "revitalize" the ingredients while also taking away some form the new fluid, but the second drain/fill should get you to about 80% every 60k imo.

On all my previous cars i have just done a drain/fill on the AT without any issues.

Keep me posted on how the M1 goes with your diff, as long as you dont feel any difference in sound or performance then i might go that route as well, since i have not been able to find any 80w90 in any of the nearby stores

 

I recently used Royal Purple Max Gear 80w90 in my diff and have had no chatter or ill effects. But, it is almost $20 per quart!
Also, Lucas Oil has a new product called ATF conditioner. It is supposed to PREVENT wear and breakdown of the fluid and also extend the life of ATF fluid. I havent used it yet but it could be worth the $10-15

 

^ good info! do you have the sports diff(VLSD) or regular?

 

nvm, just checked your public profile and seems you have a S so you have VLSD... how many miles since swap?

 

1000 miles or so.

 

Just did a full service for my car: changed MT fluid, clutch fluid, diff fluid, cleaned air filters, added prestone fuel system cleaner and replaced cabin filter. With all this done in one day, the drive right after was a day night difference! The car was starting to feel sluggish for a whole now probably cause of dirty filter, fuel system and diff. but now the car feels as good as new.

But boy what a pain doing the diff if you dont have a good high jack and then my torque wrench wont fit on the fill bolt cause the head was to big... anyways with some maneuvering i was able to do it, other than that it was a an easy quick job.

My MT oil was in almost great condition really but the diff was super dirty, the magnet had a lot of junk on it, i did a 1.5 change glad i did it right.

For those who care, i used Nissan MTF 75W85 for the MT tranny and Valvoline synblend 80w90, since that was the only oil with that exact weight rating all others were 75w90 but i wanted to stick with factory recommendation and its a bit more thicker at colder temp so a bit more protection. The drive was super smooth and quiet than before with no chartering. All update if i remember after a few thousand miles.

Oh btw for those who care the torque specs for the diff and MT tranny fill and drain bolt are 26ft-lbs.

 

Thanks for the update! You beat me to it. I was supposed to get the ATF fluids and metal washers/gaskets today, but it was sent to my old address. Might be next weekend before i get to this.

For the differential, i take it it's a 10mm hex for both drain and fill holes, right?

 

Yes 10mm hex socket for both on diff, and i reused the old washers cause like you said they are not crush washers and are actually hard metal washers that dont need to be replaced, when i went to pick up the MTF fluid and asked the guy said they have NEVER changed the washers on any cars cause its not required since there is no real wear or tear on it, but if you get em for cheap then changing it wont hurt.

 

Thanks! So, i changed the diff oil today (and the front sway bar), other than a little issue with the pump the whole process was quite easy. I went ahead and replaced at least the drain washer (the one that was already there was a bit crushed, and it seems the dealership tightened the living daylights out of the bolts).

Now i was checking the ATF and noticed an issue, will post a separate thread on that.

 

By the way, while researching on something unrelated i unintentionally looked at later editions of the FSM for the G37s. 75w90 is now the new recommendation, along with being able to use Dexron VI ATF for the power steering fluid (The '07 FSM still shows Dexron III/Mercon).

 

FWIW, I used Amsoil Gear Lube.

 

I could be wrong but wouldn't a 75W90 actually be a little bit better than a 80W90 due to the fact it's a little less viscous at start up (cold) temperature? Or is gear oil not the same as engine oil when it comes to viscosity? I was just looking to see if Red Line carries the 80W90 but, alas, they also only have 75W90.