1995 Chevy Corsica

If the light comes on, it could just be a sending unit. However, if you hear a knocking from the engine, that means the pressure is too low and will eventually cause internal damage. It could be a bad oil pump or too thin of oil. You can confirm that by renting a mechanical gauge which will plug into the oil sending unit location. You should have at least 10 PSI at idle (minimum)

Let me know what you find.