I should have said "at operating temperature" in my post above.
My '52 228 GMC engine still has its original pistons. I don't know if the crank and rod bearings have been changed. I've driven it over 40,000 miles since I bought it in 2013, but the instruments had been changed out for newer electronic gauges just before I bought it so I have no idea what the total mileage is.
When idling hot with the A/C on at 400 RPM oil pressure is 8 PSI. If I turn the A/C off the idle goes up to 425 RPM. That 25 RPM gain increases the oil pressure to 9.5 PSI. These measurements were taken 8 years ago with a 4" diameter 270 degree sweep oil pressure gauge that was supposedly correct +- 1psi. Oil is 15w-40 Rotella.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12
'52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
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