All I can tell ya is when I replaced Mobil 1 Advanced Fuel Economy 0w-20 with Pennzoil Ultra Platium 5w20 the increased Density of the PUP was very noticeable. It seemed so much "thicker" that I may switch to Pennzoil Platinum 0w20 for winter for easier starting. I don't wanna go thicker than the the Pennzoil Ultra Platium 5w20 at this time. Just my experience with these 2 oils in my 17 Camry 2.5. YMMV
That's strange because according to past datasheets, Pennzoil tends to target their viscosities towards the lower end of each range, at least that was the case a year or two ago.
But to be perfectly honest I haven't looked closely at their 0w-20 offering. But I did look across their product range enough to feel like that was a purposeful design decision their part and not mere happenstance.