Smell of Essence : Gasoline and Gasoil are hydrocarbons consisting solely of carbon and hydrogen atoms and correspond to the molecular formula (C6H6). There is naturally benzene in crude oil, a colorless, highly volatile and flammable liquid. Gasoline was widely used as a solvent until it became known that it was carcinogenic. Gasoline used in service stations is a mixture of hydrocarbons, including gasoline, which has a gasoline content of 1 to 4%. Gasoline is added to gasoline to increase the octane rating, which improves the engine’s ability to ignite.