oil pressure gage... reading when ignition is off/on?

With key off, most stock electrical gauges will read last reading before key was turned off. Mechanical gauges go to "0" when engine off.

Thank you acauth1...

mine (mechanical) is little to "0" when ignition "off", when ignition "on" and engine off needle turns acw pointig to west.
When engine running it goes between 0 and 30.