Diff Fluid=75w90NS or regular 75w90
 

im about to perform my 30k mile service. which includes tranny and diff fluid change. trans im using Redline MTL and for the diff ( '04 GT= LSD correct?) i wanted to use Redline also, but i saw NS and regular. which one is for use in the stock LSD diff?

I use Redline 75w90 in my diff.

Since the factory diff is a vicous coupled type, there is no need for the limited-slip friction modifiers. Like Jon said, standard 75W90 is fine.

DIY thread. I used Red Line 75W90 in the diff 2. And yes to ( '04 GT= LSD correct?)

keh thanks guys for evryones help. looks like im gettin the standard 75w90.

Yes, it is an LSD but it uses heat-sensitive fluid instead of clutches for the engagement.

Heat-sensitive fluid - I did not know that. What's the advantage of this design vs using clutches? How often would you recommend changing the diff fluid?

Unless you want to rebuild/buy a new transmission, stop using MTL, its too light, and oh yes it will mess it up. Use MT-90 for Tranny. or Any Tranny Fluid meets GL-4 spec thats 75w90 weight.

For Rear diff, use 75w90. Or anything that meets GL-5 at the same weight or something higher like 75w140.

the NS one is NOT for use in LSD, NS means it does NOT contain the fiction modifiers required for Limited-Slip Differential to function.

whoops i actually have MT90 not MTL haha i read all about that MTL stuff before i switched it when i first bouhgt it last Oct. my bad. but im staying with MT90 hahaha.

NS works well in the gear box - true story ...

so then i have to ask whats the difference in the MT90 and 75w90-NS, in thE gear box?

Think you are mixing up cars... the factory LSD is a Torsen type on the RX-8. I have pulled a couple apart now (the differential fits perfect in the 87-91 Turbo RX-7 differential case) and they all have been Torsen types, not Viscous LSDs.

The Nissan's use a viscous, but Mazda hasn't for 10+ years.

Yes, you are correct! I did get things confused but even the Torsen is a clutchless design, isn't it? My point is the same but for the wrong reason.:lol2:

It does work.

NS is just a GL-5 fluid without the stuff for LSD, which is good for Synchos in the gear box.

If you guys saw the various fluids I have run in my trans and diff you would think I was an idiot. Well, you may already think that, but.............:uhh:

Anyway, all the fluids we have been told NOT to use I have used without incident.:dunno:

Yes, you are correct in that the Torsen (like the Viscous) is a clutchless design and regular GL-5 gear oil can be used (although I don't know if I would use a GL-4 like MT-90 in any Torsen type diff, just because of the higher percentage of gear/tooth contact).

/\ i'm a bit the same (except for the idiot part ;) )
I've run stock , MT90, LWshockproof and now NS in the g/box . The best so far has been the NS :dunno:

Castrol sells the Hypoy-C 80w90.... also compatible with rear LSD per manual.

not as bad as a friend who put 2 quarts of atf in a old datsun during a oil change. when we changed the oil it was freaking weird looking. car ran fine though. he was a pack rat and still had the bottles in the box. finally put it together after looking.

NS = no slip modifiers

the only reason to run NS in a diff is if it's a clutch type and you're trying to induce more lockup, so there's no advantage/reason to use it in the RX-8 OE differential

slip modifiers can cause synchro engagement issues though, so running NS in the trans is a good idea, my preference is still Redline 75W-140NS

I have Kaaz 80W90 oil in the diff because I had it around at the time, not cheap ...

Cool thanks for the info Jon!

you guys are confusing me... so using NS is okay?

Don't use NS, it doesn't have the modifiers needed for your car.

not OK for diff - but OK for gearbox ...

75w90 NS =Tranny
regular 75w90 = Diff