dirtysocks,
AFAIK and as mentioned by others the oil level needs to be dangerously low for the low oil level sensor to light. It certainly won't light if the engine is only a quart or so low. Larry Bible makes an excellent suggestion for testing that the level sensor is functioning. If you use an oil/liquid extractor when changing your oil you might check the function of the level sensor as you suction out 1 quart, 2 quarts, etc. so that you know at what specific level the sensor energizes the trouble light on the dash. Too bad this thread wasn't posted before late yesterday or I would have verified the sensor function when I changed the oil in our 1991 300CE the day before.