Mobil 1 FTW:
Mobil 1 Selected as Factory and Service Fill Motor Oil for New Nissan GT-R Multi-Performance Supercar
If it's good enough for the GT-R, should be good enough for the Z.
^After doing some more research on esters, it seems like there may be some real needed benefits that the Nissan Ester Oil brings to the VVEL system (esp. in the long term). And what's more, since we don't know exactly what esters are in the oil, you can't just go out and buy a Group V synthetic ester oil and hope it does the same thing. So, until I find out EXACTLY what is in the oil I am probably just going to stick to using the Nissan Ester Oil instead of Mobil 1, or any other synthetic for that matter.