its a fair point ................ but I am not up to speed on the relevant viscosity curves in comparison in relation to temperature . Its an interesting question .
I would just say that for the normal punter the book recommended oil is what you should use .
A similar point is that the S2000 engine recommends 5W30 , or 5W40 . I use Honda s own brand 5W40 . Dont know who makes it but hey , who cares as long as its the recommended one .
oils and standards is a minefield , with dozens of different specs ........ Lifes too short !!!