What is the fuel mixture for 50hp mercury blueband?

I have found with my circa 86 blue band that for example if you put in 13 litres of fuel double that in your knoggan and add a zero you have 2600. Then turn that into mls of oil... so 260 mls of oil to 13 ltrs of fuel. Hope that helps its worked fine for us. Relax and go BOATING !!