Oil pressure light flickering sometimes

I tried everything, oil pump, 15w-50, straight 50w. Turns out I broke loose a lot of gunk in engine and clogged 4 different oil filters. Finally wound up with a WIX, don't know if its the best but its oiling well now. :) 15w-40 Rotella Diesel oil and getting 50 PSI cold and 25 Idle. Drops to normal 10 PSI per 1K RPM after hot.