What is the Gas to Oil Mixture for My Outboard?
The short answer is 50:1.That is 50 parts gas to 1 part oil.
Most outboard motors run this mix. Some very small outboards tell you 100:1 but I recommend you run 50:1. The logic here is that I would rather replace an occasional spark plug then blow up the motor. The decision is yours but that is my 2 cents.
Some older outboards 50's, 60's and some older recommended mixtures as oil rich as 24:1. Oil has changed alot since those days. I leave it up to you to decide in these cases.
Mixture chart for 50:1 ratio
1 gal gas to 2.6 oz oil
2 gal gas to 5.1 oz oil
3 gal gas to 7.7 oz oil
4 gal gas to 10.2 oz oil
5 gal gas to 12.8 oz oil
6 gal gas to 15.4 oz oil
Most portable out board tanks are 6 gallon tanks. The most common practice is to mix 1 pint (16 oz) to the 6 gallons of fuel that they hold.
To calculate any ratio you want for mixing your oil and gas simply take 128 (the number of ounces in a gallon) and divide it by the mixture you want (24:1 use the 24 or 40:1 use 40).
The result will be how many ounces of oil you should add per gallon of gas to achieve your desired mix ratio.
For a 40:1 mix 128/40 = 3.2 so you would add 3.2oz of oil to each gallon of gas to achieve a 40:1 mix.
For a 24:1 mix 128/24 = 5.3 so you would add 5.3oz of oil to each gallon of gas to achieve a 24:1 mix.