So after my oil pressure light came on after being on the dyno, I changed the pressure switch, worked fine for a week, took it back to the dyno and it came back on, I then changed the oil and lots of crap came out, none of which was magnetic (see picture below, open in new winow for enlarged view) I also changed the pressure switch again for a genuine one from Audi, oil pressure light still comes on every now and then, I checked the pressure and its within the normal range. What else could be causing the light to be coming on? Im starting to think maybe its electrical or maybe con rod bearings as I can drive it for miles without the light ever coming on, then it can randomly turn on but if I just switch the engine off and back on... The light goes out and usually stays out.