Want this question answered?
Web site never did answer the question.
Take it to a marine repair shop or google it up, the answer is there
The 1977 model, 20 hp Mercury outboard, requires a 50:1 fuel to oil ratio.
What is the fuel to oil ratio for a mercury 9.9 hp 2 stroke engine?
If manufactured after 1965, an 80 hp Mercury outboard requires a 50:1 fuel, to 2 cycle oil ratio.
The 1973 model, 7.5 hp Mercury outboard, requires 6.8 oz. of gear oil.
In the fuel tank
50:1
The 20 hp Mercury outboard requires a 50:1 ratio, one pint of 2 cycle oil, to six gallons of fuel.
A 25 hp Mercury outboard requires a 50:1 ratio, one pint of 2 cycle oil, to six gallons of fuel.
The 4 hp Mercury requires a 50:1 ratio, roughly one pint of 2 cycle oil, to six gallons of fuel.
The 2.5 hp Mercury outboard requires a 50:1 ratio, one pint of 2 cycle oil, to six gallons of fuel.