How to Mix Two-Cycle Oil in Boats

by Ryan Hotchkiss

Two-cycle engines use a gasoline and oil mixture. If you fail to use the proper amount of oil, the engine will seize. If you run the engine too rich -- too much oil in your oil and gasoline mixture -- you will foul the spark plugs. The difficulty in mixing two-cycle oil is figuring out the ratio you need to comprise your mix.

Read the owner's manual for your boat engine. Inside you will find the gasoline-to-oil mix ratio. It will probably say something like 32:1 or 50:1, but can be as low as 16:1. Always use expect a higher gas to oil ratio, more gas than oil. Using the exact mix ratio is critical. Different engines use different ratios for specific design reasons. Guessing will cost you. Running rich -- too much oil -- can be as destructive as running lean.

Convert the amount of gasoline and oil you have into liters. If you have a full 1-gallon gas can and a quart of oil, for example, you have 3.785 liters of gasoline and 1.06 liters of oil. If you have 32-ounces of oil, you have 947.2-milliliters. You can convert ounces or quarts into gallons instead, but the fractions become daunting. It is simplest to convert everything into liters and milliliters. Then you simply have to remember that there are 1,000 milliliters in a liter.

Pour the correct ratio of oil into the beaker in relation to the amount of gasoline you have in the can, then pour the oil into the can. If you have one gallon of gas, for example, you have 3.785 liters or 3,785 milliliters. At a 50:1 ratio, you need 50 milliliters of gas for every milliliter of oil. Divide your 3,785 milliliters of gas by 50 and you discover you need 75.7 milliliters of oil for your gallon of gas.

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