I do know of the quality of Esso XD 0W30. I bought a case several years ago and used in successfully (UOA confirmation) even in a 4 cylinder engine as well as a 6 cylinder.
I am looking a bit ahead to a new car with a Direct Injection engine. I plan to couple of early oil changes and then for the next, which I will sample for analysis, I will choose a GM
approved oil (read warranty). That is an oil satisfying GM6049M. As I recall M1 0W30 and Petro-Canada 0W30 are the *only* ones on the list of this viscosity.
I know there are probably many oils
without this accreditation that are superior e.g. XD and German Castrol (I have some of this in my basement

). But given the lack of financial resources at GM for the foreseeable (sp?) future I do not want any excuse, no matter how minuscule, of a rejected warranty claim by the
General.