Oil light flashes and buzzer comes on above 2200 rpm. Problem was
solved by cleaning the terminals on the double connector (near the
thermostat housing) that connects the two sets of brown wires from
the engine sensors to the front of the car. It's down low in the
engine compartment, and is the one connector on the car that's shown
such corrosion.

Thanks for all the advice that led me to understand this once-
mysterious system.

Jim