'89 100 oil pressure warning. Electrical wierdness or big problem?

[SuffolkD at aol.com]

Tom:  We may need more info.
Oil level low?

While the heads up display may be a sensor gone bad. There are two AFAIK:
 The VDO pressure gauge is usually pretty accurate.
I had a 20V 3B "rebuilt" LOL, and the "parts guy" put thin weight oil in 
which is good to get all around the motor.........but it would be 1bar at idle and 
3bar tops at 3000 RPM.
I switched out the oil to thicker 10/40W and the gauge is 2.5 (idle) - 5bar 
at 3000 RPM.

What is the oil viscosity..........generally older motors have large 
tolerances where thicker oil does better.

I think its Bernie who generalizes: higher pressure doesn't mean higher 
flow.................
as I interpret him
HTH - Scott by BOSTON

The victim is a 1989 100Q sedan with approximately 160k. This just started
happening, and it's very erratic. The oil pressure light on the computer in
the dash will issue a warning, and then go off while driving. 

The car will idle, totally warmed up with the temp needle in the middle of
the gauge at just under 2 bar. The oil temp seems normal, although the gauge
registered just under the middle after 1 hour of driving (some highway, some
stop and go) in 90 degree weather when the warning light issue first
manifested itself.