0W-16 Oil for Gen 4 Prius (and other cars)

I was wondering whether anyone has experience with using 0W-16 grade oil for their Prius (or other cars)?

From reading Japanese websites and the Japanese market Prius owners manual, 0W-16 appears to be factory fill for Japanese domestic market Priuses. Not sure if this the case for other countries (yet). It seems adapting engines to accept ultra low viscosity oils like 0W-16 is another further step towards improving fuel economy.

Here in Australia, 0W-16 seems to be tricky to get; I would be interested to know how easy it is to get in other countries and how expensive it is (I'm guessing very expensive!).

Just for your reference, here are a few 0W-16 products I've found:

Ravenol (Germany)
RAVENOL Extra Fuel Economy EFE SAE 0W-16 - Ravenol

Penrite (Australia)
ENVIRO+ HYBRID 0W-16 (Full Synthetic)

ENEOS (Japan / US)
ENEOS Launches 0W-16 Motor Oil With Next Generation Technology | ENEOS

 

For your interest, I've attached a picture from the Prius (ZVW50 series) Japanese domestic market owner's manual which lists recommended oils.

[translation below]

"Engine Oil Recommended Viscosity

Use the chart below to determine the optimum engine oil viscosity according to the temperature conditions.

* Your car is filled with 0W-16 oil at the factory when new, and it is the best oil for optimum fuel economy"