320 deg F oil temp OK?

There is some discussion on Ferrarichat re what the max allowable oil temp is. Everyone seems to agree that in the 1980's about 265 deg was the highest that should be allowed. But some folks are saying they routinely see 300 deg in their Ferrari 360s on track days. One fellow quotes an oil engineer as saying that with Mobil 1 or other synthetics 320 is fine and even 340 for a short time is OK and if there is a failure it will not be due to the oil or lubication. At what point does oil simply no longer lubricate or should one consider the oil to be ruined and replaced before the car is run again?