Bearings and oil wt vs clearance

Was going to put this in the duratec section, but anyway doesnt mater what motor really.
How do you decide whats best for a higher reving motor... I have no idea
lets say 9000rpm and specing the bearings either no less than min clearance or no more than max clearance for whatever motor factory specs. Whats the consensus for high rpm hp motors?
Whats the best way to go large mains bearing clearance and heavy weight oil, high volume pump.
runs the risk of low oil pressure at idle and oil scavenging issues at hi rpm causing burned mains.
or
Tight tolerance motor high pressure pump light weight oil.
run the risk of oil failure bearing wear, piston wear, cam bucket follower wear
I know danny was in favor of running grease as he use to say.. but went off the idea later why?
regards Paul
How do you decide whats best for a higher reving motor... I have no idea
lets say 9000rpm and specing the bearings either no less than min clearance or no more than max clearance for whatever motor factory specs. Whats the consensus for high rpm hp motors?
Whats the best way to go large mains bearing clearance and heavy weight oil, high volume pump.
runs the risk of low oil pressure at idle and oil scavenging issues at hi rpm causing burned mains.
or
Tight tolerance motor high pressure pump light weight oil.
run the risk of oil failure bearing wear, piston wear, cam bucket follower wear
I know danny was in favor of running grease as he use to say.. but went off the idea later why?
regards Paul