I took my boat out over the weekend and was on the water for about 8 hours but not running the motor to much when running down the lake I got an alarm saying Starboard Oil Tank low. I checked my oil tank and the oil was only one inch from the top of the oil tank. Any ideas ? I installed the Merc monitor just before I put it away for the winter and I did not install any sensor on the oil tank due to not getting one as far as I know.