The owner's manual calls for 0W-20 oil that meets MS-6395 specification, and nothing but. Doesn't matter if you are operating it in the desert or the arctic. Thats the oil they say to use, thats the oil you should be using, period.
said, the engine was built very specifically
for the particular viscosity of oil it calls for. The engine oil is used as hydraulic fluid in narrow passageways managed by extremely high-precision timing of solenoids that influence intake valve lift and duration to make up the "Multiair" system.
You want your engine to run like crap? Go right ahead and mess with the oil viscosity, see how that works out for ya.
Want it to wear out sooner too because of improper lubrication? Try some randomly selected oil viscosity based on your natural expertise combined with something you read on the internet.
You want to give the dealership a fantastic reason to tear up your warranty and flush it down the toilet? Go ahead and mess with the viscosity some more. Tell them all about how you, in your infinite wisdom, decided that 0W-20 was far too "watery"....
they will love that. They will love never having to work on your vehicle for free again, anyways.
The difference between 0W-20 and good ole 10W-30 is not really that extreme in terms of viscosity but with the minute tolerances they can build for bearings, the tiny passages they pump the oil through, and the extreme amount of precision computer control that is ultimately using the oil to vary intake valve timing and duration... nobody has any business messing with that. The most important thing to do for this engine is to keep the oil clean (change it and the filter often) and only use the oil its spec'd for. No funny additives or friction modifiers, just straight high quality synthetic oil.