bad sender, bad connections, bad instrument panel indicator.  or worn out
engine (rings, pistons, cylinder walls, pump, lifters, valves, head ....
).  doubt that it is weather related, as you are north and it was raining.
Hot weather and wrong oil for conditions can bring on low oil pressure, but
it usually shows up when it is really, really hot, and upon dropping engine
speed, not at highway speed as it sounds like yours did.  But people more
knowledgeable than I am may respond, hopefully.

On Mon, Jul 18, 2022 at 8:41 PM Mark Pinnell <mark.stuart.pinnell@gmail.com>
wrote:

> Hi all,
> Just made a very quick exit from Hwy 20, just east of Montreal as my oil
> light came on, solid. Just over 400 miles covered today.
> 1985 1.9l  Oil level appears to be OK, no different smells out of the
> engine bay, and no noticeable difference in engine sound or performance
> (I'm using that term loosely).
> It's slashing down rain, as it has been all day. Luckily, we're in a
> service station, so we can bed down for the night and see what the morning
> brings.
> Interested in any thoughts that the group may have as to what the cause may
> be, possible diagnostics, etc..
> Mark
>