Oil alert problem

[John Lagnese]

Hi,
My 91 200 TQ 20V has an annoying problem. The dash display will go off
sounding the oil alert while driving. Sometimes it goes off on starting from
a stop usually it occurs during driving. The oil pressure gauge shows 4.5 to
5 bar. The gauge appears to work, the pressure goes down on idle.
This seemed to be the high oil sending unit. I changed that (the white one)
to no avail. Any ideas? Any BTDT?
Thanks,
John