[Jacob13]

AutoZone is slipping then. In my local Walmart they now have like six different 0W20s:

Valvoline
Quaker State
Mobil 1
Castrol Edge
Pennzoil Platinum
Supertech
and others will follow soon

In my humble opinion, unless there is something very different about Mazda's skyactive engine, all of these are pretty much equal. Just buy whatever you like the most. I just got QSUD 0W20 for our Prius because Quaker State will send you $20 rebate if you sign up for their "warranty" program. Free oil is always good, QSUD is basically like PP, at least they come from the same parent company and VOAs look very similar. Every once in a while NAPA also has a good sale of NAPA Synthetic (and that's basically a Valvoline synthetic)

 

[Jacob13]

A lot of guys on Bob is the oil guy will disagree regarding Moly being required as a signal for high quality oil. For one, there are anti-wear additives that work just as well. For example, sodium-based Valvoline turns out pretty good UOAs. Next, you don't always know if the Molybdenum additives comes in the more sophisticated tri-nuclear form or not.

There was always a long debate about 0W20 vs 5W30 and I don't think this issue has ever been settled. In any case, I don't think there has ever been a hard proof of thinner oil being worse for the engines, specially when its recommended. Don't forget that the 5W30s when they're recommended, are often recommended in non-synthetic form. By the time the 5W30 is out of the pan, it can shear down to 20 grade anyways. A synthetic 0W20 should be shear stable and stay within its viscosity grade longer. As engines are redesigned, tolerances decrease and in that case the thinner oil should actually protect better.