That would not account for loss.
Yes, oil can leak through the switch.
Bad oil pump, low on oil, bad oil sensor All motors oil pressure drops at idle speed Just be sure it's not in the too low range
Low oil pressure.Oil level extremely low. Faulty oil pressure sending unit. High mileage/worn engine bearings.
Erratic oil pressure is usually caused by a bad oil pressure sensor.
oil pressure sensor bad
The most likely answer is the oil pressure control switch (aka oil pressure sending unit). costs around 4 dollars and 5 minutes to replace. It's right behind the distributor cap. Bad bearings , a whole in the block , or a bad sending unit . Which one sounds most likely ?
Loss of oil pressure.
Low oil, no oil pressure, bad sending unit, wiring, bad gauge,.............
The oil light is an "oil pressure" indicator. it means you have lost oil pressure or the oil pressure sensor is bad
oil pump/ main bearings/ severe oil leaks/
If you indeed have no oil pressure, then the oil pump is probably bad. But saying that, are you sure you have no pressure? The oil pressure sending unit can be bad or disconnected. Also the pressure gage can be bad. An oil pressure test will verify if you indeed have no pressure. Not sure of the engine size but I know on a 2.3l the timing belt can be suspect to although rare if the engine is running ok, and if there is truly no oil pressure you should hear the lifters banging/ and or bottom end knock.
From the easiest to the hardest oil in oil pan,bad oil gauge, bad oil pump bad cam or crank bearings.