Typically, gasoline and oil shouldn't mix, and it's really bad if they do. However, there are instances in which you have to mix oil and gas together for a particular engine to work. This applies in the world of lawnmowers, for example, where its motors require the use of 2-stroke or 2-cycle fuel. In a 2-stroke motor or engine, this oil-and-gas mixture not only provides a source of power for combustion. But, that small percentage of oil also lubricates the engine's internals, as well. To properly mix oil and gas, you have to get the gas-to-oil ratio right. Usually, it's a 40:1 mixture, meaning that for every gallon of gasoline you add, you'll need to include 3.2 ounces of special 2-stroke oil. Just pour them together into a gas can, and make sure you reference a manual to find the right ratio.