87' convertible oil light goes on-off randomly

So, yesterday evening my oil warning light started going on off after a 25min drive.
A first it flashed quickly but randomly. Then only a few minutes later it started to stay on for longer periods (multiple seconds).
It didn't matter if i revved the engine high or low, the behavior stayed the same. Also cornering or breaking does not seem to have an effect.

I checked the oil level, it wasn't high, but still a millimeter or 2 above the minimum. So i added half a liter oil this morning.
Then took off and unfortunately again after about 25min's the same behavior occurred.

So it's not the oil level. I guess it should be there oil pressure (pump swap?)?
But why does it take a 25 min drive before the light goes on? Surely the engine and oil is on temp way before 25min. So I cannot believe it's the oils viscosity (thinner when warm, so more prone to pressure loss?) causing this?
Btw it was already reasonably warm here this morning, 20c Celcius.

Any info more than welcome!🙏

Have your Pressure checked with a mechanical gauge.  it should be 2 bar at 2000rpm when the car is up to 80degrees c

Replace your low Pressure at high rpm, that is the White Sender on the oil Filter flange.  Being that there was no buzzer it could also be the oil pressure circuit behind the speedometer it is "l Shaped"

If you are not running 10W40 or 20w50 oil and a good Mann or Mahl filter change it.
Last do no use Generic, Fram, Store branded, or Bosch filters.

Is this only at idle or RPM if at Idle then your Low oil pressure side of  oil pressure switch on the side of the head may be bad as well.

I had similar symptoms to this on a 1.8 GTi. The oil cooler slide valve was not opening and therefore oil not going to oil cooler. I fixed this and oil light never came on again.

Hi all,

There is clearly aan electrical issue in my car. Two days after this the alternator died.
I replaced with a new one and never got the weird oil light issue again. So that seems resolved.
But once in a while the car just dies while driving. This means no electricity at all anymore. Everything goes off as if someone would pull the battery out. Engine stops, including dash and the clock resets to zero. Normally i can immediately restart the car after that.
I think it had it more often with the old alternator. So I actually thought it would be resolved with the new one. But had it again yesterday evening.
I already checked power and ground cables left and right but could not detect any major issues.

Any ideas where to start checking first?

Bad Ignition switch comes to mind, and also how may key's do you have on your Key-ring.

I had a daughter that had about 20 lbs of things all attached to her key ring and occasionally from the pendulation of the Keys, the weight would cause the keys to turn off the ignition.  

I told her only 3 keys were allowed, the Ignition, and the 2 house keys.  Since then no issues.

Don't discount bad ground cables frame to engine and engine to transmission/engine.

If yours are still oem, they are approaching the end of life.

Briano1234 said

Bad Ignition switch comes to mind, and also how may key's do you have on your Key-ring.

I had a daughter that had about 20 lbs of things all attached to her key ring and occasionally from the pendulation of the Keys, the weight would cause the keys to turn off the ignition.  

I told her only 3 keys were allowed, the Ignition, and the 2 house keys.  Since then no issues.

Don't discount bad ground cables frame to engine and engine to transmission/engine.

If yours are still oem, they are approaching the end of life.

Haha, thanks for the advice but I just have the car and fuelcap keys on it, and that should obviously not reset the clock etc.

All is still OEM and looks good (but I know that doesn't mean anything when it comes to cables).
Thing is that the way it cuts off everything in a blink, it makes me feel like a cable with a loose or bad contact. And it should be one of the main cables like going to battery out alternator i guess. But checked the already… :-)

Another thought on bad ground cables is that I had a Oldsmobile that when it was 50 degrees and humid, the car wouldn't start.  I rebuilt the Dizzy and the car started and didn't have any more issues until it got to be 50 degrees and drizzily.
Low and behold the car wouldn't start again.  I got a bit miffed, and recheck all the battery connections and such, and since it was cold and my hands were wet,

I threw my hands up with disgust, and well the spanner I was holding flew out of my hands and landed against the frame, and the Negative post of the battery, and Sparked.  The light went off in my head and I grabbed a set of battery jumper and ran them from the battery negative to the frame and from the battery negative to the engine.  The Frigging car started and ran great.  I disconnect the Ground cable
and cut the sheath off and about 8 inches back from the battery terminal end  the cable was totally green and crusty with corrosion for about 8 inches…… Bad Grounds.