Note that the nitro name is generally inaccurate, as nitromethane is usually not the primary ingredient, and in fact many glow fuels, especially the so-called "FAI" type, named for the Fédération Aéronautique Internationale, which requires such fuel in some forms of aeromodeling competition, contain no nitromethane at all.
Nitromethane is added to the methanol to increase power and to make the engine easier to tune.
Four-stroke model engines, since they are generally designed to be simple power plants while still incorporating the usual camshaft, rocker arms and poppet valves of larger sized four-stroke engines, are generally meant to use glow ignition and their fuel.
The nitromethane in many glow fuel blends can cause corrosion of metal parts in model engines, especially four-stroke designs, due to the nitric acid residue formed from combustion of nitromethane-containing fuel, making the use of a so-called "after-run oil" a common practice after a model flying session with a four-stroke glow-engine-powered model (This is a common myth.
The problem is methanol is highly hydrophilic which means it absorbs moisture from the air and deposits in on the various parts of the engine which is what causes the corrosion blamed on Nitromethane.
)[citation needed] Glow fuel is not difficult to make, and so many modelers mix their own to save money, but some of the ingredients are flammable or explosive and so can be dangerous to (and difficult to obtain for the general modeller), especially in large quantities.
Another form of model fuel used for small compression ignition engines is called "Diesel Fuel" and generally consists of kerosene, ether, oil and some sort of ignition improver, usually amyl nitrate or isopropyl nitrate.