Doesn't matter very much. That variation is insignificant compared to e.g. the non-being level of the tractor when you check it. Explosion engines are practically only binary sensitive regarding the quantity of oil: it is there and can be pumped around with sufficient pressure, or it isn't there. You need enough to keep the pump intake from running dry when you're leaning or climbing and not so much that you smother the moving parts. The oil pressure is independent of the quantity; the low level depends on the quality of the oil pump, the high level on the setting of the overpressure relief valve in the circuit.
