Hi my oil light is flicking on and off at idle when hot, oil levals ok no leaks 800rmp

got an oil pressure display witch is reading 4ish lb# when hot and 40 lb# when cold at idle? it will go up when reved?

not sure if its oil grade or pump on way out?

 

4lb when hot, jesus that's low, I'd swap the oil right away, is the car high mileage ?, may just be getting very worn or shit oil, try a thicker grade ie a 50 instead of 40 etc if it's got loads of miles on it, will help the pressure problem, don't need a huge amount of pressure at idle anyway, but wouldv'e wanted higher than 4lb idleally.
tabetha