This topic has been covered many times on the forum.
So once more
IMHO best to use Genuine Nissan Fluids.
For 6 speed manual transmissions use MT-XZ fluid: SAE 75W-85-API GL4+
For VLSD Differential use SAE J306: 80W-90 API GL-5
All in stock and good to go.
Alex.
Thanks Alex, I appreciate an experienced opinion.
However it's not what is best for the car I'm concerned with so much as whether I will cause any active harm with what is in there at the moment. If it's not the best then it can wait for the next service or so, if on the other hand I'm ruining something with totally unsuitable fluids then I want to get it out quick!
Millers and Motul make some very good fluids, however I am not sure if these fluids are correct or 100% suitable for your particular application.
There are many members on here who have added after market fluids only to find that they are not really suitable and they have had issues. Most have been caught in time and the fluids drained and refilled with fluids that Nissan recommend for the 350Z.
Better safe than sorry would be my thinking mate.
Alex.