I have a 2013 Silverado with the 5.3 and 4,500 miles. I am wondering what is the best motor oil? Not just guessing, are there studies that are not biased that indicate one is better than the other?

My truck requires "special" oil is what someone told my father who has an identical truck. However, I think he may be referring to the "dexos 1" designation GM requires for their vehicles. I am not sure.

Also, does anyone know what the recommended weight is for this vehicle?

I appreciate it!