First you need to determine if the oil is the correct viscosity and is not contaminated with fuel
and the filter is not stopped up and the coolant
is the correct temperature.
Next you need to determine if you actually have low oil pressure or a sender is not functioning properly. It has been my experience that the sensing system is less reliable than the engine
oiling system and therefor is prone to producing inaccurate readings.
The simplest and most reliable test is to install a known good mechanical test gauge in the engine oil gallery [where the sender is attached is probably the best place] and run the engine through a normal load and temperature cycle while observing the accurate gauge. You do not require a special gauge a commercial
1 or 2% gauge with correct pressure range and face marking from McMaster.com is acceptable. I personally us a 3.5" 0-100 psi / 0-700 KPA gauge with a 270 degree swing with 1% accuracy marked in 10 psi increments.
You need to determine the correct fitting prior to purchasing
the gauge to get the proper gauge. A short section of automotive power steering
pressure hose and some adapters and hose bibs will make the connections
After determining accurate oil pressure you can continue with your troubleshooting.
Never ignore low oil pressure readings!!