Really haven't figured out why a 0w20 would be needed except in the most blistering of cold weather. I would side with a 5w20 probably because, in general, it should be more VI stable than 0w20. At least the perception would be that. And given the abuse the oil has to take with the AFM feature on GM's light duty engines, it would seem a 5w20 would provide a slight edge. Just glad I don't have to deal with it with my 2015 2500 6.0L. Those still have recommended XXw30 oils.