Re: Mariner 50 low oil warning
If the reservoir is on the motor, then the oil level sensor is in the reservoir itself and having oil in the lines and pump make no difference to the sensor. Its very common for the magnet part of the sensor float to break off and fall to the bottom of the tank thereby fooling the system into thinking its low on oil.
Someone here posted a procedure for reattaching the magnet but most will tell you to replace the reservoir or simply unplug the sensor and keep an eye on the oil level. Thats what I did 2 years ago now.