Systems and methods of monitoring lubrication of a gear assembly during operation of a machine provide for receiving at a control system, a signal from a sensor indicative of a value obtained by the sensor for an electrical property of a circuit crossing the gear assembly operably coupled to the machine, ascertaining whether the value for the electrical property corresponds to a warning level for a condition of the lubricant film, and outputting a control command when the value for the electrical property corresponds to the warning level for the condition of the lubricant film.