The dashboard gauge that indicates oil pressure. When this gauge lights up, it indicates a very low level of oil in the engine, which should immediately be replenished. The direct indicator of the condition of your engine. If the oil gauge gives very low readings, it means that your oil pressure has dropped. Not all cars have oil gauges, most australian built cars simply have an Oil Problem Indicator that will light up if the car has low oil. Nevertheless, the oil lights are not as reliable as the guage.