Thanks for the lucid explanation about the need for 0w16. I wasn't aware of the reason why. I have the same engine in my Venza. I'd like to go with Toyota 0w16, but l just couldn't pass up Mobil-1 for $22/5qt so that's what l will be using.1) it's not an AR-series engine. It is a A25A-FXS (Dynamic force)
2) use the 0w-16. The owner's manual says if it's not available, you can use 0w20 as a substitute and change back to 0w16 at the next oil change.
Why? the A25A has a variable discharge oil pump that is also ECU controlled. The ECU controller is programmed around 0w16.
What oil to use? Well, the Toyota 0w16 is quite stout with tons of Moly in it with a healthy dose of Boron.