It would be a simple matter to wire a buzzer or a warning light through an oil pressure light switch that would indicate an "ignition on- - - -engine off" condition. Once oil pressure builds up within a second or so of engine start, the warning system would shut off automatically, and stay off as long as there's oil pressure present. Most of those switches have a 7 PSI turn off pressure, so it would also serve as a "loss of oil pressure" warning.
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