It's hydrodynamic pressure that provides protection.
Desired
oil viscosity is based on a couple things....two of which are:
1. Bearing clearances
2. Your environment
Most of my street engines run about 30 psi at idle and 70 psi going down the road. I use 10W-30.
I've been following your threads and you are way overthinking the
oil to the top end deal. The internet can be helpful in a lot of cases. It can also be totally out in outer space in a lot of cases. There are a lot of engine "experts" out there who 1. Have never laid hands on an engine 2. Don't have a stinkin clue about what they're talking about.
IMO, you just got a set of junk heads.