Just got done changing my diff oil. My car is at 25,000 miles ish and i read somewhere that a diff oil change can be good for the car.

So ya, for all of you that have never done this, best 30 mins of my life. The car rolls sooo much easier now, so less revving when clutching out from a stop. It rolls easier on hills and stuff too. Generally speaking, just the acceleration feels a lot smoother. I'm glad I did it. I'm pretty sure it was a premature change (it didnt need to be changed yet) but there was SO much nasty crap that came out of there.

If you have never done it, i recommend it.

 

What kind of oil did you use?

 

i used Castrol Syntec Full Synthetic 75W-90.

I'm going to use Redline oil in my trans when i do it next weekend, but i had to special order GL4 instead of GL5.

For those who dont know, GL5 in the transmission will damage the synchros... FYI

 

speaking of synchros we have the same as the 6 speed frontier. isnt that something.i know 2nd is the same and think all the others are as well.

 

Stick to amsoil for all fluids. It might show at their site but sign up to get info to buy wholesale and it shows(from an outside test not amsoils) in the brochures that they have the best viscosity on all fluids(doesn't break down as fast as other fluids). Plus they have a XL version that just the filter needs to be changed after 7500 to continue until 15000 before filter and fluid need to be changed to save money on oil changes. I do mine at 6000(filter)-12000(both) and have seen a difference in the fluid(stock though not FI).

 

thanks. ill keep that in mind. i try and change my oil every 4,000 miles just to be safe. its a little cost here, that saves a LOT of cost later.

 

Exactly my assessment right after I changed it....

it's time and money well spent.

 

You guys can actually feel a difference in performance just from changing the differential oil?

 

I measured a signficant performance boost on my Gtech-RR doing immediate before/after. It not only felt smoother, but the car was faster.

The rear diff is a significant component of drivetrain loss. When I changed at 18k miles, metal shavings and stuff that looked like poop came out at first, then eventually some clearer fluid. yuck. change it - you won't regret it.

I think I used royal purple... you should replace the crush washer - the part number is listed on a thread here or on g35driver.

 

when i did my diff it was for the heat issue mainly.i am using rp now but will be trying motul next.you'd be surprised how much heat you lose by adding synthetic.and along with a aluminum finned diff cover, that would be even nicer.

 

Here's how it all went down for me:


New car -> felt great to launch and drive

7k miles-ish -> clutch started to feel weak, like it wasn't grabbing hard enough. Had to rev to higher RPMs to launch

10k miles -> problem got even worse. I considered buying a new grabbier clutch, but before I did that, I changed trans and diff fluid. the diff fluid was all black and full of metal shavings. After changing the fluid, car would roll without assistance on VERY slight inclines that it would not previously roll on. Lower RPM can be used for launching now, clutch "feels" stronger.

18k miles -> problem is back... I am going to change out the diff fluid (only) again. I assume that the diff was not done breaking in. Hopefully this time the fluid will last longer. Scratch that... I don't think the fluid is at fault, it's just that the diff is still breaking in...


Changing the Diff fluid made a huge difference in feel. The transmission fluid felt pretty similar before and after. But, the transmission now works like BUTTER when it's warmed up. So I sacrificed some cold shifting performance for excellent warm shifting characteristics.

 

.

 

I think synthetic trans fluid should be good for 60k-100k easy.

 

sure does. I had to special order too. the guy kept saying that 350z are newer cars and that they take gl5

 

Nevermind I found it