Depends how your warranty is. Nissan are very, very specific about the auto transmission oil - they allow "or similar" for everything else, but they specifically want THAT oil for the auto transmission.
It's to do with the way the torque converter works. Different grades of oil will cause the converter to behave differently. You would find that a heavier oil will cause the car to creep more, and idle lower, as the oil doesn't let the converter slip as much. A lighter oil might not let the converter "grab" as much, so power transfer would be less effective (it'd be like a manual with a worn clutch).
That said, if you're out of warranty, there's no harm in trying it. If you can't sell the oil to someone, you could give it a go and if it suits, there's your oil for the next few changes.