You roll your eyes at me? I'm so sorry you doubt me my fellow american, but I have oil viscosity charts right here in my hand.

At operating temp, rougly 212°F both a 0-30W and a 10-30W have an absolute viscosity of 0.010 Ns/m2. This is the viscosity that the engine parts were designed for.

At 70°F 10-30W has a viscosity of about 0.170 Ns/m2 which is 17 times higher than the optimal viscosity.

At 70°F 0-30W has a viscosity of about 0.035 Ns/m2 which is only about 3.5 times higher than the optimal viscosity.

So you see that even here on the temperate central coast of Cali 0-30W is still by far the best choice in viscosity. And as the temperature gets cooler the differences in viscosity only get much further apart.

Now keep in mind many believe that roughly 80% of all wear occurs on startup. Wouldn't it make sense to select an oil that that starts flowing and protecting quicker than the other oils while still maintaining the correct operating viscosity?

Now, you may tell me why you doubt me.
-Chris