OVERKILL
$100 Site Donor 2021
I mean, that's the philosophy behind the wider spreads, that they are appropriate for a broader range of conditions and are less viscous on start-up, so they have an advantage in fuel economy as well.So the wider the spread is better to a certain extent, is 0W-40 the perfect Viscosity depending on where you live?
The driver behind the higher base oil viscosity is the suite of approvals. This is not universal. TGMO 0W-20 for example, has a calculated BO of ~4cSt, while M1 EP 0W-20 was almost 6cSt, slightly heavier than M1 AP 5W-30 at 5.66cSt (these are estimates).