Hello.... it appears your outboard is a 1978.
The 1978 model, 75 hp Mercury outboard, requires a 50:1 ratio, roughly one pint of 2 cycle oil, to six gallons of fuel.
1978 80 Mercury Outboard IDLE ADJUSTMENT
1978
A 50 hp Mercury outboard, serial number 5111678, is a 1978 year model.
1978
A 15804b is a 1978 motor.
The 1978 model, 9.8 hp Mercury outboard, requires a 50:1 ratio, one pint of 2 cycle oil, to six gallons of fuel.
A 9.8 hp Mercury outboard, serial number 5208019 would be a 1978 year model.
248lbs is the weight of 115 hp chrysler outboard motor
The 1978 model, 115 hp Mercury outboard requires a 50:1 ratio, one pint of 2 cycle oil, to six gallons of fuel.
1 quart of outboard / 2 cycle motor oil to 6 gallons of gas