Unless its different on the euro cars you don't have a oil level light on your car. IF your talking about the row of green leds and yellow and red then thats the service due indicator. The more greens lit the longer time until the next service is due. Some of the cheaper models of e34, e36, etc didn't come with a oil level sensor in the bottom of the pan, they just have a block off plate, hence no wires for one.