I have the same problem with the oil light coming on periodically
especially when it has been raining or really humid on my 91 Integra.  I
have also replaced the oil sending unit. The light will come on full red
sometimes, other times just dim red...... this has been going on for 2
years now. The light may come on for days, the go off and not come back
on for weeks.    As long as I know there is oil in the car....which I
check weekly, I just keep driving it......248K miles and running strong.
I am thinking it possibly could be a bad ground somewhere.

I've searched this group for previous messages and noticed that the oil
pressure light has been mentioned a few times. When it's been raining for a
long time it comes on, flickers, or is real dim. In addition the headlight
chime also chirps randomly during the same weather conditions. I never knew
that the chime even existed because it doesn't work as it's supposed to.
I've replaced the oil sending switch and problem still exists. Tried
connecting a mechanical oil guage to test pressure but am having problems
finding right fitting for block connection. Standard 1/8 inch thread only
turns in about 1 1/2 turns and I don't want to force it any further.
There seems to be a Technical Service Bulletin # 90013 called "Engine- Low
Oil Pressure Light Flashes". Can anyone tell me what this bulletin is about?
Any help greatly appreciated.
Kindest Regards,
Robin