Oil Weight Question?

[Vettster]

Originally Posted by Desert Dan

Most new engines are using lower viscosity multi weight oils like 5-30wt.

I am not sure why? That would be an F5 question
Maybe higher tolerances require thinner oils or the 5-30wt lubricates better?

What about in extreame heat 110 degrees plus is the 5-30 good enough?

Part of the reason is for fuel savings.
Living where I do, I always use heavier oil.
Mobil 1, 15-40 or so.