2007 Grand Prix GT (supercharged)here, 89,000 mi.
Any quality 5w30 will keep this car happy. Use any oil you wish within reason; yours may still be )under warranty (if you purchased from a GM dealer) as is mine (for a few more months/miles).
Changing oil today - PP 5/30 with Fram XtdGuard (the good one).
I've used it all - PP, PU, RP, QSUD, M1EP, Synpower.
OLM is roughly 10k, I do OC every 6,000 mi. I use a 1/2 qrt over 6,000.
Enjoy the new ride. Last of the GP's.
At your mileage I would change the trans fluid and consider replacing coolant this year or next. Check your PS fluid. It is so hard to get to most places don't check it (cause they can't find it (rear of engine, by the passenger side firewall).