If not using the oil injection system, a 150hp Mercury outboard would require a 50:1 ratio. This is roughly, one pint of 2 cycle oil, to six gallons of fuel.
50 : 1 is the correct fuel mixture
A 4hp Mercury outboard requires a 50:1 fuel to 2 cycle oil mix.
I have a 1984 90hp Mercury outboard and the fuel mixture is 50:1 which is one pint of 2 cycle motor oil for every 6 gallons of gas.
The 1984 model, 9.9 hp Mercury outboard requires a 50:1 ratio. This is one pint of 2 cycle oil, to six gallons of fuel.
50;1
50:1
50:1
50:1
50:1
I have a 1999 Mercury 2stroke 5HP outboard and the owners manual states 50:1 Gas/Oil mixture.
20/1
the mixture is 50:1