I have to say I skipped a few bits of this thread but it seems another area where a lot of crap is abound!
Racing engines running to 8.5krpm don't ever need pressure above 4 - 4.5 BAR.
So no poxy road cars gonna need it.
Oil should provide high pressure when cold then as it heats up the pressure will drop until the engines revved.
A lot of engines at hot idle will drop pressure, some older cars will even go so low that the oil light will flicker (rover V8's are good for this), this won't cause any damage as long as the pressure rises.
So 6BAR etc are silly figures unless of course your running into 5 figure rpm's.
All you do by upping the pressure is increase parasitic drag and increase the likliehood of blowing out a core plug.
If you need high oil pressure to avoid failures it means the oil lube system is crap and needs attention.
What do Vaux recommend the pressures to be? I can bet the farm that 6Bar ain't the figure!
copper core rads not popular then with the 5 crew
i would cry with less than 2 bar at any point, even these rover v8s, the pressure light is 35psi (not sure if thats standard, but thats the switch my mate had in his cobra rep)