Yesterday, driving to work, all the sudden my oil pressure "gauge" dropped to zero while idling. As soon as I revved it up, boom, back to normal. Every time I hit idle, it dropped to zero. Then returned to normal once the revs hit over 1000. On the way home from work, didn't happen. I suspect the sensor is going out. I just bought the car in November, it has near 116,000 now. Runs great. Well cared for by previous owner.