Rumor has it NASCAR folks like low
oil pressure, less parasitic loss from the
oil pump so they keep it at "just enough" to do the job. I suspect the rule of thumb of 10 psi per thousand rpm is valid.
But for myself, I'm not trying to eek out every last fraction of a horse power by reducing my
oil pressure. While 10 per thousand may be OK I don't have a problem with twice that, or whatever.
TO much oil pressure COULD be a problem how ever. Extra stress on the oil pump drive shaft has been known to twist and break them! Over a certain amount and the oil by-passes the oil filter. If you are running "high pressure" it's certainly important to keep the rpm low to reasonable until it warms up.
We ran 50 wt. in the Formula Fords, but were careful to keep the rpm low until the oil warmed up. I don't have a problem with 30 psi at idle at 100 c myself, 45 is not some magic number.
Another reason I don't care for
synthetic oil is the long oil change intervals usually recommended. My position has remained unchanged for decades on this subject, in spite of "new studies". People ask what oil I prefer, I tell 'em, use a good quality brand name and STICK WITH IT and change it often.