We run Mobile 1 0w-40 (OEM GTR and Viper fill) plus Mobile 1 filters.
Reason for the 0w-40 is that it consistently shows very good wear characteristics in oil analyses, and mobile oils tend to run on the thinner side. Ie, the 40w is really more like a 35w and the mobile 1 5w-30 oil after it's been used for a while breaks down to about a 20w.
Another great choice would be Amsoil 5w-30. Just don't buy into the nissan ester oil crap. You'll pay $100 for an oil change and still not have that great of a lubricant in your engine.
Man I love oil threads...
