Check your manual for the proper gas-and-oil mixture. For almost all modern two-stroke engines, a 50-to-1 mixture is recommended. That requires about 2 1/2 oz. oil for every gallon of gasoline.
Use only two-cycle oil for your mixture. This oil is made especially for these engines and can be purchased at gas stations, hardware stores or any other place where you buy regular motor oil.
Pour the proper amounts of gas and oil into a fuel can. Shake the can well to mix it.
Label your gas can with the mixture ratio. You can use the same mixture for other two-stroke engines.
Shake your fuel can thoroughly every time you refuel. After a while, the oil will settle out of the gas, and shaking it up ensures that the oil and gas are properly mixed again before you put the fuel into your chainsaw.