The same type of gas is used for both two-cycle and four-cycle engines. Use only fresh, regular gasoline. Old gasoline does not ignite easily. Store gas in a safety gasoline can, never in a glass container.
When you refuel your engine, do it on a driveway or over some dirt, not on the lawn or in your garage. A little fuel almost always gets spilled, and not only is gasoline quite volatile but it also kills the grass on contact. Also, be careful to never refuel a hot engine—it can be very dangerous.
You must mix the gas with oil for two-cycle engines. The proportions of gas and oil vary from one piece of equipment to another; see your owner’s manual for the exact proportions to use on your machine. Two-cycle oil usually comes in small pint-size cans that are convenient for mixing with one or two gallons of gasoline.
To mix the oil and gas, you can pour the appropriate amount of oil in a gas can and then fill the can with the appropriate amount of gasoline at the pump. If you have more than one two-cycle engine, be sure to keep separate cans for each, labeled and clearly marked with the proper proportions of gas and oil.
Diesel versus Gas
More and more of the larger garden tractors now have diesel rather than gasoline engines. Diesels are commonly used on large agricultural machinery, and they have many advantages—not the least of which are cheaper fuel and an engine that will normally outlast a gasoline engine. Diesel engines do not have spark plugs. Instead, the air and diesel mixture in the combustion chamber is ignited by the sheer pressure of the rising piston.
Diesel provides more heat per gallon; gasoline provides more energy per gallon. Not only that, but diesel also saves fuel by mixing with more air. And the absence of a spark plug and a carburetor means that there are fewer parts to go wrong.
Never let a diesel engine run out of fuel, or the fuel lines to the combustion chamber become filled with air. They then must be “bled” (drained) to make room for the fresh diesel fuel.