sounds like the oilways might need a clean out. how often do you change oil? how do you drive your engine? it could be that if you rev the pants off it that the bearings no longer hold the oil pressure like they should. maybe a faulty oil pump, although this is not common. the oil pressure switch in your block operates at about 5 or 6 psi i think, thats bugger all with metal flying round 1000rpm. if your lights on you got a problem. if it goes out after a while somethings on its way out. does your engine knock at all?