Comparing Amsoil SS , M1 EP , and Castrol Edge EP 5w20 oils. From what I can see on paper (actually the monitor) , all three of these oils look pretty good. It appears that the M1 and Edge are just slightly heavier at 100°C with an 8.9 compared to 8.7 for the SS. At 40°C we have SS @ 50.2 , M1 @ 49.6 , Edge @ 45.1. Based off of that info, the Edge seems best for a vehicle that sees summer and winter driving. Not sure just how important pour point is, but the SS has lower numbers than the other two. The SS also seems to have the best NOACK specs, which may not be incredibly important, but at 5.5% it looks pretty pressive. Now we come to VI. Both M1 and Edge are rated at 161, whereas the SS is only 153. What does this mean in real life? I've always read that the higher VI , the better. Is VI reason enough to choose one over the other? We all know that SS and M1 EP are pretty highly regarded oils. Most Castrol products here don't seem to see much love or respect. Though all three of these choices surely will be more than adequate for use, and all things being equal with pricing or availability, based on manufactures info, which would be considered the "better" or even "best" of the three? Assuming this is a generic engine that is simply spec'd for a 5w20 oil without any specific details.