Light diesel oil or LDO, is a blend of components from the distillation process of crude. It is used in engines with an rpm less than 750, such as boilers and furnaces. LDO is also referred to as distillate fuel or marked oil. A diesel fuel is any fuel suitable for burning in diesel or compression ignition engines. Diesel fuel is a mixture of hydrocarbons obtained by distillation of crude oil. The important properties which are used to characterize diesel fuel include cetane number (or cetane index), fuel volatility, density, viscosity, cold behaviour, and sulphur content. Diesel fuel specifications differ for various fuel grades and in different countries.