If you have low oil pressure it could be a tired oil pump OR increased bearing clearance in the bottom end of the engine. You could try to replace the pump with a high volume pump or in the meantime use a thicker oil. I would put 20W-50 in your crankcase unless you live in Alaska…its too cold there for that weight of oil. The thicker oil will be able to fill in the extra clearance opened up in the bottom bearing and increase your oil pressure.