I have read articles on VVT and cam phasers, and apparently thicker oils can impede the operation of the cam phaser.
The problem is though, that the auto industry and its apologists are just telling too many whoppers about viscosity, and it's to the point that no one believes them any longer, and anything they say about viscosity is suspect.
It's one thing to mention fuel economy and North American driving habits. I can buy that. When you start to mention viscosities available in other locations, well, that's getting a little more questionable, but I'll live with it. Then, people start to really fling the manure.
Manuals have wording warning of damages from the wrong viscosity, yet two sentences later say a different viscosity might be needed in the cold or in extreme heat or high speed use. Which is it? Then, people talk about clearances differing. Clearances are the same all over the world. A Honda (or Ford or whatever) engine in Europe isn't put together so sloppily that it needs 15w-40 or 20w-50 there while needing 0w-20 in North America. Nor do I buy that VVT is that sensitive to viscosity, or they'd only sell the engine in the tropics. If a VVT setup won't work properly with 5w-30 in Texas because it should be running 0w-20, then it's surely going to have a hard time in Saskatchewan in December, even with a 0w-16. An A3/B4 oil isn't going to throw a monkey wrench into the works by any stretch of the imagination.