There are a few oil threads around and there is never a clear winner in the best one. Best I've used is mobil 1, but I'm not that fussy with this car. Anything at least semi-synthetic should be pretty good
The vs ecotec is specified to use 20w/50 so i'd be going with something pretty close to this viscosity. Dont go too much thinner though otherwise they tend to develop noisy lifters. Personally i'd recommend Penrite oils, specifically HPR30 which is a 20w/60 or HPR15 which is 15w/40 and semi-synthetic. A nice score too, only 64k.