To use a fuel-to-oil ratio mixing chart, determine the ratio of gasoline to oil that the relevant two-stroke engine requires. This is listed in the owner's manual, or somewhere on the engine. Then, find the chart that displays the corresponding gas and oil values for that ratio. Search for a specific amount of gas, and look in the oil column to find the amount of oil the gas needs to be mixed with to create the appropriate ratio.
Fuel-to-oil mixing ratio charts display different amounts of gasoline and oil that create one of several common mixture ratios for two-stroke engines, such as 100:1, 50:1 or 25:1. These ratios mean that for every 25 units of gasoline, for example, there is one unit of oil present. Individuals can determine these amounts themselves, by dividing the amount of gasoline they have by the left side of the mixture ratio. For example, to create a 50:1 ratio for 100 gallons of gas, an individual would mix 2 gallons of oil, or 100 divided by 50, into those 100 gallons.
Two-stroke engines require oil to be mixed into their fuel because they do not have dedicated lubrication systems. To mix gasoline and oil for two-stroke engines, pour oil into an empty vessel, and then gasoline on top of it. Then, close the vessel and forcefully shake it, until the gasoline and oil are fully mixed. Before using a mixture that has been sitting, shake it again to avoid separation of fuel and oil.