Abstract: An internal combustion engine includes a lubricant level maintenance system. A reservoir is located externally of the engine. A pump is connected to the reservoir and a conduit leads from the pump to the engine oil pan. An electrical level sensing circuit includes a thermistor which is positioned in the engine oil pan, preferably by means of an engine dip stick. An enabling circuit is connected to receive an input from the sensing thermistor and from the engine electrical ignition system. The enabling means responsively provides an enabling signal to the pump following the elapse of a predetermined time interval when the engine is turned off. A tilt switch disables the sensing system to prevent distortion of the thermistor signal if the vehicle is parked on an incline.