changed rocker cover on my v yesterday drove around fine all evening then had it turned off for few hours went shop last nite and oil light kept coming on and fading away again checked it for oil and all seemed ok kept happening coming home to now checked for loose wires or anything cant find anything light only coming on now it goes off if i rev the car past 2000 and goes off when it drops clean pcv vavle started oil light came on but then faded away after few seconds ?? need help lads