Nothing raises blood pressure like the subject of oil pressures and grades. The conventional wisdom is that tickover pressure is relatively unimportant, as long as it flicks back up to a sensible level when the engine is revved and like a number of you, I have had numerous classics and old cars that have done this for many tens of thousands of miles without any undue problems arising. Gauges too can be unreliable, I have had engines in prewar cars that produce lower oil pressures on the gauge when cold, than hot, presumably because of the difficulty of the cold, thick oil in getting down the feed pipe to the gauge. Also, the pressure reading does vary according to where the pressure takeoff is located.
Very high pressures would worry me, forced leaks, especially into the clutch housing must be a potential issue with higher pressures than originally designed for. I have used the Halfords classic 20/50 for some time now, but before the National, decided to treat my car to one of the Penrite oils, since it was likely to be conducted in hot temperatures. They recommend their Shelsley Medium, which is a 25W70 oil. I think that oil pressure at tickover was improved slightly, but the higher pressure whilst running seemed unaffected. I may return to the cheaper oil when the next change comes around.
Julian Pratt
Editor FP