Oil pressure switch . I had the flickering at idle . I changed the switch out and it continued to flicker only after it warmed up and at idle. I did some reading and used a quality engine flush , changed out the oil and added cheap filter , drove around the block a couple times and added a new filter after dumping the oil and adding a heavy duty diesel engine oil(on sale at walmart for $12 for a 2 gallon jug) and an a S.T.P. oil additive for extra oil pressure & lubercation. I have not had any flickering oil pressure light come on since ! This worked for me . I did check the oil pressure before any of this at the port were I replaced the oil switch and I had almost 50lbs. If it was lower I might not of spent the money for all of this ?

 

Let's analyze this. Big engines or small, when oil heats up, it gets thinner and the pressure drops. It is really dramatic on 3000 hp locomotive engines. When a positive displacement oil pump runs slower, it pumps less oil, so the percent that leaks back past the pump gear spaces increases. So it stands to reason oil pressure is lower when warm at idle. Add to that the fact that bearing clearances increase as engines wear, then you have conditions where a good switch for a new motor starts to flicker for an old motor. Bumping up the viscosity, like Mike K did, is the traditional method to solve the problem.

Every pressure switch has a trip point and no two are exactly the same. That is probably why the white version is different than the black. In one sense if the oil light flickers at the stop sign, and you have checked to know the pump normally produces good pressure, then you can be sure it will warn you when it's seriously low.

Thanks for indulging me. I love analyzing stuff