The oil pressure readings wil also vary with the temp of the oil. At idle you will see higher readings with a cold engine than you will on an engine that has just been running on plane. On my old '88 I get about 40 at idle when cold but it will drop to 20 after coming off plane. Then if the engine idles for a while the oil cools off and then the oil pressure reading will creep back up to 40. At speed it will max out at about 65. The viscosity of the oil you use also affects this. Conventional multi Vis oils will show lower hot pressure readings than single viscosity oils or oils blended for marine use like the Merc 25/40.
You'll get different readings with different gauges.
The sending units can vary the readings as much as 20#
Age,dirty oil, hot engine can affect the readings.
The important thing is that it's showing at all and the motor's not ticking or knocking.
My Burban runs at 60# then warm is 40# (diesel)
