My girlfriend 88 Nova has just over 150,000 miles on a perfectly maintained 1.6L 4 cyl. Carb. Engine (4A-LC). It run well, there are no ticks, knocks, or squeals. The oil light briefly flickers while the car is stopped, in drive, and at an idle. If I switch it into nuetral before I come to complete stop, the idle is high enough to keep the oil sending unit from turning on the oil light. I understand that the oil pressure may be low enough to damage the egine before th light comes on, I just like to keep the light form coming on. I bought a new oil sending unit, but I have neglected to put it in yet, as I no longer believe this to be the problem. I heard that post examination of engines with catastrophic failure due to low pressure, often have fully functioning oil pumps. There are a few questions on this site similar to mine, and the answer was replace the oil pump. My understanding of an oil pump is, it is more of a recirculator/restrictor, rather than a traditional pressure building pump. Also I noticed a dent in the oil pan, the dent is within 1-2 inchs of where I believe the oil pick up screen to be. Do I need a new oil pump if changing the sending unit, oil pan, and inspecting the pick up screen doesn't work? I apologize for my long windedness. Grin. Thank you!
First check the oil pressure with a mechanical gauge. The electric senders can go bad as well as the wiring to it (high resistance giving false readings).
If the pressure is low it could be main/rod bearings excessive clearence in the oil pump or possibly a restricted oil passage (sludge).
If low oil pressure is comfirmed, the oil pump clearence would have to be checked as well as bearings on the crank and rods. All this would get very expensive, so you may want to get a used JDM engine or a good used 4A-LC and replace it.