First of all thanks for the read!!!
Narrow viscosity oils like 0w-30 (diff 30) or 5w-40 (diff 35) require far less VI Improvers and therefore are less prone to "shearing".
What u are saying here is that u are better off using a 0w-30 oil then using a 14w-50 oil ? as that's what i understand from it. As from how i understand and read its doesnt shear as much but say in a performance engine it will shear anyway as it gets too hot (over a standard engine) and then will require more VI Improvers?