As mentioned, it is all about how your engine is setup. Old school loose clearances thick oil. One main reason for the loose clearances is a stock block was designed for what, 400HP and we build them to 700HP the block moves around during hard loads. Loose clearances absorb this deflection. I use 20W50 VR1 for years in my race car. Modern engine good stiff block tighter clearances 10W 30 or thinner. Almost all of my builds for street engines get 10w30 Lot of hydraulic roller lifters now will not work correctly with oil thicker than 10w30.