Oil pressure low light came on after oil yesterday.

Potentially could be an oil pump, as if you have a situation where oil pump pressure drops due to a failure in the pump, the motor could make some noise from lack of oil and the MIL light/Oil Light would illuminate due to lack of oil pressure.

Keith, it probably is the oil pressure light.

Low oil level causes low oil pressure. But, as you say .. your oil level is okay. It may be the oil pressure sender which is at fault. There's every possibility that your oil pressure is fine, but the sender is sending a false signal to your dashboard which gives the 'low oil level' warning light.

Get the mechanic at your local dealership to stick his head under the hood. You'll get a diagnosis in seconds. I don't think you have too much to worry about .. just that 'low oil level' warning light is a bit unsettling ..

The warning light means the engine oil pressure is low, not necessarily that the oil level is low.
The problem could be the pressure switch, or you really could have low oil pressure.
Driving the car with low oil pressure will damage the engine.

suspect bad oil pump or clogged filter

Low oil pressure, you need a analoque guage to check it. Could be the oil pressure releave valve.

The thing to do is to remove the oil pressure sender and put a mechanical oil pressure gauge onto the fitting. Start the car (if it will start) and watch the mechanical gauge. If there is no oil pressure or very low oil pressure (less than 5 psi minimum), immediately stop the engine. Engine damage is sure to result with oil pressure that low. The cause of the low pressure will have to be diagnosed and corrected before running the engine again. Causes of low pressure could be worn engine bearings or a worn out oil pump. There could also be a restriction in the oil system such as a clogged filter or clogged oil pump pick up screen in the oil pan. The oil itself, if it is dirty and full of moisture will become like mayonnaise in the bottom of the pan at such cold temperatures and the oil pump will not be able to pick it up.

I know this won't be easy to do in -20 degree weather. But your car should be towed home or to a shop and not run again until this oil pressure check can be done. I'm hoping damage has not already occurred.

sounds like bad oil sending unit

first check the wire going to the sensor, give it a good clean on the conditions. if this does not sort the problem it could be because of the oil change, muck in the oil could of gotten into the sensor, you maybe able to clean it out but you may need to replace it. when an oil change is done they would put a cleaning agent in with the oil, this loosens any burnt oil off the engine, this burnt parts can stay in the engine and float around and even block the pressure sensor.

Check the connection where the wire plugs onto the sender unit. If it's loose, or the wire shorts out to the body, it might flicker. If this isn't the problem, unscrew the sender unit and check your oil pressure using an oil pressure gauge screwed into the same hole. The pressure should be above 40 psi if my mind serves me correct. If it's too low you'll have to replace or check the oil pump. Did you replace the oil filter and oil recently? If the filter is blocked or the oil is old it might also cause the pressure to drop too low.

I had a similar problem with my 2003 Sante Fe (intermittant problem, the light went off when I accelerated). I took it to the dealership. They looked for a bad send oil switch (not the problem) as well as some other possible culprits but could not, at first, find what was causing the light to come on (but they did confirm that I had low oil pressure). So, they took the engine apart. What it was was the pan was "dented" upwards, so that less oil was able to come in. It wasn't the bearings. It wasn't the crank case. It wasn't the oil pump. So, they fixed the dent, put everthing back together and . . .it worked! The light went off and stayed off. It cost $337 in labor. I was very very very relieved.

(Apologies if this explanation is hard to follow-I'm no mechanic and am basing my response on my understanding of the mechanic's explanation).