I would stay away from most 0W-20s (
especially your 'faves' the TOY/Idemitsu variety), NO MATTER WHAT his oil pressure/temp gauges say. The stock boost on that engine is fairly high, as is the stock WOT enrichment programming.
The TOY stuff
might be OK if he lived inside the Artic Circle during winter time, but otherwise, I would avoid it like the plague
in THAT powerplant.
An engine no matter how powerful doesn't know what grade of oil is in the sump just what the operational viscosity is at any given moment. That's why you can run a 0W-5 qualifying oil in a NASCAR engine flat out for a few laps as long as the oil temp's don't exceed say 180F.
An oil pressure gauge is effectively an onboard viscometer.
GM V8s can run safely with OP in the low 40 psi range without issue at high rev's consiquently 50 psi is a very conservative lower limit which translates into a fairly viscous oil.
Since street driving so under stresses a high performance engine it is very easy to run a light oil as the oil temp's usually stay very low.
Since most owners of high performance cars are (I hate to say) poseurs that drive no faster than you're typical Prius owner, they don't need to run a heavy oil and the lubrication demands of the engine would be better met in running a lighter than spec' oil.
OP is how you determine what the correct oil viscosity is for any application.
By your OWN admission, the TOY juice (don't know about the Honduh stuff) shears down to ~ a 2.2(?) or so HTHS VERY quickly, which
could be dangerous to that engine
even if he (or anyone else) drives it like a 95 year old granny in her Avalon, since NO ONE changes it out after < 10 miles as the teams do with "qualifying oil" (which I'm not sure of the rules, but might actually be in special "qualifying" engines
).
It is
NOT a Prius hamster wheel motor!
Have you personally ever owned, and/or raced an LSx series engine?
