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As long as you use a synthetic and anything that meets GM standards you will be fine. Factory fill is Mobil 1, but you will find many have an array of opinions when it comes to oil.
The debate on which oil is best is as debatable as who makes the best beer (Sam Adams and Stone btw ).
That being said, I prefer Mobil 1 5w-30. It's readily available and sometimes goes on sale at Wally World for around $25 for a 5 quart jug...can't beat that. Get another quart and a half, plus a Mobil 1 HE oil filter and you can do it yourself for around $50-60. Don't forget a new drain plug gasket too!
I only use Penzoil Platinum 10w40 because I live in a hot climate. Its a good oil. I first used Mobil 1 but after changing to Penzoil Platinum I noticed the car runs a little smoother. Could be that's just what my car likes idk but works for me. I do use Moble 1 in my transmission though. The car had around 80,000 miles on original tranny fluid when i changed it and the car now shifts as smooth as butter.
I fly large radio controlled airplanes and in the RC forums we always have what we call "oil threads". I didn't know car forums had them too. Anyway for me it's Mobil 1 5W30 in all my cars.