From: Kenneth Mackenzie <kmackenz@u.washington.edu>

	I was driving the van about 1 week ago down a major arterial,
	and the oil pressure light/buzzer came on.  The van has about
	99K miles.  The short story is: oil level is ok and the engine
	is not overheated.  I heard no knocking ( although now all I
	remember is the buzzer).  I parked the van asap and let it sit

I really don't know anything about engines, but I am used to debugging
computer programs. From your notes, I see that:

M1: Oil light comes on
    Oil pressure with warm engine 0.5 bar

M2: Oil light does not come on
    Oil pressure at 3000 rpm 2.0 bar

M3: Oil light does not come on
    Oil pressure at 3000 rpm 30 psi ~ 2.0 bar

The problem is intermittent, but real, and the sensor is good.

I have a VW Golf with a similar problem: When driven warm at medium RPM
(which means it happens only on vacations, in the mountains) the oil
pressure warning comes on and stays on. It only happens after a half 
hour of driving and the mechanics insist that they absolutely cannot 
duplicate it however detailed instructions I give them. I first saw it
the day after I picked it up new in 1985, and since it has survived for
10 years, I guess I should stop worrying about it, but it still scares
me when it starts, every year, on the second day of vacation, halfway
up the Sierra Nevada ...

My vision is that a piece of lint rag or something is floating around
in the engine block channels and half blocks the channel in front of
the pressure sensor.

/ Lars Poulsen - 85 Golf, 87 Westy