1990 V8 Oil Light On

[Joe.Oliver@alltel.com]

I have a 1990 Audi V8 Quattro.  It has 122,000 miles on it.  I use Kendall 
20-50 W oil and change the oil every 6,000 miles.   It has a intermittent 
problem with the oil flow light coming on.  The oil pressure guage is 
showing 5 bars all the time at speed and does not go below 2 bars at idle.  
The light will come on, stay on for a little while and the go out.  Does 
anyone have an idea of where to look for the problem ?