Nitro-powered 1/8-scale and .21 engine remote controlled cars take a blend of nitromethane and oil – either synthetic or organic – according to About.com. There are several different blends of this nitro fuel, with varying oil-to-fuel ratios.
Organic oils in the mix, such as castor oil, can help cool the engine, while synthetic oils can help thicken the coat on the moving engine parts. The oil mix in nitro fuel is essential to the car's performance, as undiluted nitromethane could seize the engine. Many remote controlled car enthusiasts try out several fuel variations to find the one that performs best in their situation.