Is there anyone with an automatic that changed to synthetic and noticed an improvement? I'd be leary of slipping gears with an automatic and synthetic.... IT seems a very good idea for a stick but automatic? Don't you want a little tiny bit of friction (more than synthetic gives you anyway?) ....
FYI: The manual transmission uses 85W-90 OIL per Infiniti. They make no mention of any special LSD lubricant requirements. The name FLUID implies Automatic Transmission Fluid (ATF) and manual transmission OIL means gear oil (85W-90 for example) or motor OIL used in a manual transmission (5W-30). To confuse matters more, some manual transmissions even use ATF for a lubricant.
I, too, am changing the MT OIL on my 95T. I'll probably use Amsoil 85W-90 Synthetic. My question is, has anyone tried motor oil in the 5 speed gearboxes? Any autocrosser's out there use anything other than the MT 85W-90 in their SE-R's?
I was recently sk00ld in the ways of the Nissan LSD unit, and learned that it is sealed; no friction modifyer necessary, because your gear oil doesn't make it into the VLSD unit, nor would your transmission fluid if you had any.
It's very common (especially for domestics) to use ATF in their manual transmissions. I've heard of guys doing this with our cars, but I don't think it's a very good idea at all. It just doesn't sit well with me. The only transmissions I know of that use standard motor oil in the gearbox are Hondas. It's not very common, really.
Redline MT-90 is highly recommended, with Amsoil and Royal Purple also being mentioned. You probably want to stick with a synthetic, as it will shift smoother. The 90-wt is important to protect the gears themselves; if you had a turbo you'd want something even heavier than MT-90, something like Redline Shockproof (which is, like, 120-wt or something obscene like that).
The most important thing is that it be GL-4 compatible; this is a MUST. Dual GL-4/GL-5 compatibility is acceptable if the additives they use to reach GL-5 are non-corrosive to yellow metals (like bronze, the metal our synchros are made of). IIRC, Royal Purple is dual-compatible, and meets this guideline; please don't quote me, call Royal Purple. Can't go wrong with Redline MT-90, though.
In the U.S., the 94-96 P10 Touring models had the VLSD. I am not a G historian yet, so I'm not sure about the Pre-93.5 models. I would assume, knowing the Europeon car enthusiast nature, the VLSD would be optional across the whole Primera line. The code on the tranny will tell you if it has the limited slip, I believe it had the "V", but search the forum, it has been covered.