Fuel mix for 1987 mercury 50hp?

50:1 mix ratio or 75:1 guide says 50:1 recommended but see how it runs on both for you cant hurt adding too much it can if you put way too little. i ran it 75;1 this summer just to try it and it was fine

so 22litres or 6.6 gallons or gasoline is 500ml of oil with 50:1 mix