[jlthunder]

All Opels have an oil sending unit. If yours is missing, then someone removed it and replaced it with a plug. All Opels which have the gauge and light have the 2 wire unit. All others with only the light have the smaller one wire unit.

I believe the wire comes out of the firewall on the drivers side of the car. If the wire has been cut, I believe it will peg itself, but I'm going from memory.

Does the little light in the oil gauge light up when you turn on the ignition, but before you start the engine? Does it go out when the engine is running? This light is needed for the charging circuit to operate, otherwise you will be running off of the battery.

You need to install a sending unit so you know what your oil pressure is.

I don't have a schematic in front of me so I can't give you the wire colors.