Yep, but gearbox and diff oil change isn't on the Nissan service schedule at all, its just precautionary.
Plus, you will mostly be confined to the Nissan waiting room. Do you trust the dealer to do the work, even with own parts supplied?
I mean I'm sure most dealerships won't have the trainee monkey do it, but just in case you are going to a dealer that belongs to the minority.
Can you be totally sure?
With independants, like Abbey or DMS, you can see the work as it's being done, and depending on how friendly they are, you can even get your own hands dirty if you want to learn (Thanks Andy @ CS who showed me how to do brake pads on Brembos)
Another thing would be the thinking from a reversed perspective.
Customer comes in with his stuff and wants me to do the work and not use the stuff I have on my own shelf...hmmmm.
I wouldn't go to a chinese take away and bring my own steamed rice and tell them to make a fried rice for me (not that I would anyway, just an example of the top of my head)