Totally agree with you@R Veloster N Excuse me but nothing you said supports your opinion. Winter grade of oil means only how viscous it is at start up. The lesser number the better. After heating up oil will always be less viscous and that’s the whole point. You let engine warm up before driving hard because oil is too thick.
I don’t see absolutely no reason for going with 5W. Also most of us are driving on 0W30, including track days, and nothing is happening