Dexos 2 is the certification for Diesel engines. You want Dexos 1 for your C7. This site lists the current Dexos 1 approved oils.I believe it says Dexos 2 aproved oil for the Z06 C7 - ??? and a 5W30 or for track 15W50?? is this the correct??
You don't have to use Mobil 1. Any 5W30 oil which is dexos1 certified will keep your warranty alive and happy.
As for which oil is best, well, let's not open up a can of worms.![]()
I've had Mobil 1 in my car since new, because I got 4 free M1 oil changes courtesy of Chevrolet. Next change will probably be Penzoil Platinum Plus. Same price as Mobil 1 at my local auto parts store in 5 quart jugs. (Yeah, I can probably get M1 cheaper at WalMart, but I think that the Penzoil is probably better oil.) But the truth is that if you change the oil according to the OLM, and use a high quality synthetic, you'll wear out the rest of the car before the engine fails due to oil related issues.Not everyone is in the "Mobil 1" Club. Personally I use the Amsoil products in all of my vehicles.