Originally Posted by Zacc
I'm sure its Mobil 1, looking at the part no. they used its 88865635
That part number is ACDelco Dexos 1 5W30 synthetic, but there's nothing wrong with it. It's probably an equivalent bulk oil from the distributor GM told them to buy from. GM tells dealers where and what to buy for oil.
We do stock bottled Mobil 1, but it's for cars that call for Mobil 1 specifically like certain Corvettes, Cadillacs, and Camaros. They will typically have Mobil 1 on the oil cap assuming it's original.