Glow fuel is a fuel source used in model engines – generally the same or similar fuels can be used in model airplanes, helicopters, cars and boats. Glow fuel can be burned by very simple two-stroke engines or by more complicated four-stroke engines, and these engines can provide impressive amounts of power for their very small size. Glow fuel is primarily for two-stroke engines with the need for oil mixed in the fuel and limited exhaust and fuel/air between cycles. Top Fuel race cars with 4-stroke engines may also use glow fuel, but in this case it does not contain appreciable oil.