D2 diesel, also called Gasoil, is a fuel oil that is the second distillate derived from crude oil. D2 diesel products contain different levels of sulfur and require no reformers or additives to produce.
D2 diesel fuel is the broad category for the second distillate of crude oil. Ultra-low sulfur grades of D2, such as GOST 305-82, reduce sulfur content to a maximum of 0.02 percent and reduce sulfur pollution emissions.
Diesel fuel is often used in diesel engines. Diesel engines, also called compression ignition engines, rely on the temperature increase of compression, rather than on spark plugs, to achieve reliable ignition timing and combustion efficiency.
As a result of their inherently higher compression ratio for a given power output, diesel engines are more fuel efficient than spark ignition engines. However, compared with spark ignition automotive engines, diesel engines weigh more, generate more vibration and produce greater particulate or soot emissions. Diesel engines can also produce a particularly carcinogenic type of hydrocarbon pollutant known as polycyclic aromatic hydrocarbons (PAHs), which are generated during the diesel combustion process.
The cetane index is a measure of the autoignition quality of a diesel fuel, with higher numbers meaning that the engine is easier to start in cold weather.