Tractor Fuel Types
Diesel fuel first started appearing in large agricultural crawlers in the 1930s, but it was not until the 1950s that diesel became a major fuel source for farm tractors. Difficult starting limited the use of early diesel engines. Some manufacturers built spark-ignition diesel engines, or engines that started on gasoline and were switched over to diesel. Others used small gasoline "pony motors" to warm and start the diesel main engine.
By 1960, diesel engines had greatly improved and were becoming very popular for large farm tractors. By the 1970s, nearly all farm tractors used diesel engines.
Kerosene was commonly used as a tractor fuel in the early part of the 20th century. Like tractor-fuel, it was used in "all fuel" engines after the engine had warmed enough to allow efficient combustion of the kerosene. Cheaper gasoline after World War II, plus the onset of diesel engines, caused kerosene to disappear as a tractor fuel.
Starting with John Froelich's 1892 tractor, gasoline had always been a fuel for farm tractors. Most tractors built through World War II either used gasoline, or could use gasoline (in an all-fuel engine). By the 1960s, diesel was replacing gasoline as the primary fuel, although gasoline was often an option into the 1970s. Today, gasoline is only used in lawn tractors or other small equipment.
Liquified propane, or LP, gas was commonly used in the 1950s and 1960s as fuel for farm tractors. Farmers began converting their gasoline engines to LP gas in the 1950s to take advantage of the low cost. Manufacturers soon began offering these engines as an option. LP gas engines were discontinued as diesel engines began the primary fuel for farm tractors.
Known as tractor vapourising oil or distillate, this once-cheap fuel was commonly used in farm tractors until World War II. Many manufacturers built low-compression "all fuel" engines designed to burn tractor-fuel, gasoline, or kerosene. The engine was started on gasoline from a small tank, and switch to tractor-fuel once it was warm. In some nations, high taxes on gasoline (for automotive use) made tractor fuel a cost-effective alternative.
Tractor-fuel was a low grade fuel produced between gasoline and diesel in the traditional distillation of crude oil. The refining techniques developed during World War II made it possible to convert this into more useful fuels, and it began to disappear.
Power Fuel was a high grade of tractor fuel. Power fuel had a lower grade than gasoline, but higher than kerosene or distillate. Power fuel was sometimes specifically formulated to avoid road taxes imposed on automotive fuel.
A tractor-fuel engine can be run on modern gasoline. The lowest grade of gasoline available today is often better than the highest grade available when these engines were built.