Oil light at idle 
  Hi all.
 
 I raced my 916 during the weekend and it happened twice when exiting from the track after 10-12 laps to have the oil light flickering at idle. Revving it a bit made the light dissapear, but when the revs dropped it appeared again.
 
 I let it cool for 1 hour and when i started it didn't do it.
 
 Yesterday i drove it in town and no problem.
 
 I also noticed that the oil cooler looks very dirty, full of mud / dirt.
 
 What do you think it can be the problem?
 
 thanks