Oil pressure correlates much better to HTHS than to kinematic viscosity. Here's a graph showing the correlation. It was taken from
here. The original data is from a BITOG post somewhere.
The largest oil pressure drops are going to be across things like bearings, cam journals, and other restrictions where shear rates are going to be pretty high. As far as I can tell, kinematic viscosity isn't as relevant as HTHS to any aspect of engine lubrication.
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