I have talked about this before a couple years back..
It would be interesting to know the amount of flow of oil going UP to the lifters themselves.
As well as @ start up and @ hot idle. This is when it seems oil psi is at its lowest.
This is why I honestly believe in a thick coat of oil (Film Strength) as well as some type of perminate coating protecting these lifters [Moly] when oil psi or flow is low and not supplying them with a adequate amount of lubrication. If this is actually happening.
Also I was a true believer in never letting my 5.7L idle for more then 5 min... No matter what.
Good stuff. Here are a few more things to consider. The oil pumps are fixed-displacement. Pressure is defined as resistance to flow. Is higher pressure what you really want? Not exactly. More flow=more oil actually passing a given point at a given time. More resistance to that same flow creates heat and is not necessarily a good thing.
Remember, old school oil pumps were cam/distributor driven and the pumps themselves were partially submerged in oil because they were located in the oil pan, with very short pickup tubes; all parts submerged, at least partially. When you hit the key, the pump was already primed, so flow is immediate.
Since switching to distributor-less ignitions, they had to reconfigure oils pumps. Now, oil pumps are front mounted, high and dry, and are crank driven. Their pickup tubes are ridiculously long, at around ~2 feet. When the engine sits, the oil tends to drain out of the oil pump and pickup tube, back into the pan through gravity.
When you start the engine after this, it has a very long, large diameter pickup tube to travel (displace) just to prime the pump. During that time, there is actually a vacuum/negative pressure. In part, this is why less viscosity is good in this type of oiling system. Dry starts are unavoidable. This is also why many high performance engine builders opt to use dry sump lube systems. Immediate lubrication. Pump stays primed.