diff oil.what should i use
 

what should i use for my differential froma z32 vlsd...to use on my s13 .

any gl-5 rated gear oil.... i run royal purple

To supplement this. You want GL-5 rate oil for the differential, and it does not need to have an LSD additive since the VLSD is a sealed unit. Avoid using GL-4 oil in the differential.

Conversely, you should only use GL-4 oils in the manual transmissions and not GL-5 oils.

The shear characteristics of the two oils are very different. The GL-4 helps promote friction in the syncros for more positive engagement between shifts. The GL-5 oils survive better under sliding situations, which are commonly experienced by the R&P in the rear.

Rear - Any 75W-90 GL-5 oil. Royal Purple, Redline, Valvoline, Mobil-1, or any other quality gear oil

Trans - Redline MT-90, Pennzoil Syncromesh (a little light, don't use it under extreme HP), Royal Purple Max Gear or Syncromax, or a mox of the two...

You get the idea. Good luck.

Great info, I hope I bought GL-5... Otherwise, I may have to take it back.

very good info indeed bro

Quick question, Kragen recommended 80w-90 GL-5 and I bought that, it should be ok right?

yea should be ok 80-90w is factory recommended lol

i bought the 75-90w Royal Purple Gear oil for my tranny and diff hope i dont screw somthing up lol also i aint spilling one drop of that ish $10 a quart is stupid expensive

I believe 80W-90 and 75W-90 are both useable, and Nissan will recommend either depending on climate.

Royal Purple doesn't have a specific tranny gear oil, the have a tranny fluid but it's too light of weight for our transmissions. You should be fine with what you used.

So what you stated earlier, I should be useing GL-4 for the transmission since GL-4 promotes friction and GL-5 for diffs.

Did I get the correct? I would think that you would want less friction in the transmission? Or am I missing something there as well?

You've got that right. You want friction between the syncro cones. Syncros act as brake pads between the gearsets. As you change gears the syncros need to syncronize the speed of the input shaft with the output shaft in the transmission. This speed is different between each gear. You want the oil film to act as the friction surface between the syncros, not the metal of the syncro itself. That way you reduce the wear on the syncros.

Ah, I get it now! Thanks for the great info!

Mega +1 for SuperHatch!

On the topic of gear oil, has anyone used neo synthetic 75w90? Heard alot of road racing cars run this with success but not from many personal experiences. Also is it possible for a gear oil to cover multiple GL specs?

On Royal purple bottlethey say it meets performance requirements of both GL and GL5 but Valvoline it's only GL5.
So I think Royal purple it's either better for being more advanced or it's worst for not being so versatile.
I use Royal purple myself on my Diff anyways. But I don't have MT.