This is the first year I,ve owned a boat and I not sure exactly how to winterize it. I have a 1977 mercury 20hp motor. The motor has a flush plug on the lower part of the motor. Is this where I drain the gear oil and add new oil?
I own a 20 horse mercury out board motor. It is electric start with thunderbolt ignition. The serial # is 4586144. I can't find a model number. Does anybody know a year on this motor.
