D6 Virgin Fuel Oil is also known as Residual Fuel Oil and is of High–Viscosity. This particular Fuel Oil requires pre–heating to 104 ºC to 127 ºC (220 ºF – 260 ºF).
The term fuel oil generally includes any liquid fuel that is burned in a furnace or boiler to generate heat, or used in an engine to generate power. However, it does not usually include other liquid oils, such as those with a flash point of approximately 42 °C (108 °F), or oils burned in cotton- or wool–wick burners. In a stricter sense, fuel oil refers only to the heaviest commercial fuels that crude oil can yield, that is, those fuels heavier than gasoline (petrol) and naphtha.
Fuel oil consists of long–chain hydrocarbons, particularly alkanes, cycloalkanes, and aromatics. Small molecules, such as those in Propane, Naphtha, gasoline for cars, and jet fuel (kerosene), have relatively low boiling points, and are removed at the start of the fractional distillation process. Heavier petroleum products like diesel fuel and lubricating oil are much less volatile and distill out more slowly, while bunker oil is literally the bottom of the barrel. In oil distilling, the only components denser than bunker fuel are carbon black feedstock and bituminous residue (asphalt), which is used for paving roads and sealing roofs.
Virgin Fuel Oil D6 is mostly used for generators. Recent changes in fuel quality regulation now require further refining of the D6 in order to remove the sulfur (S), which leads to a higher cost. Despite this recent change, D6 is still less useful because of its viscosity as well as that it needs to be pre–heated before it can be used and contains high amounts of pollutants, such as sulfur. Since it requires pre–heating, it cannot be used in small ships or boats or cars. However large ships and power plants can use the residual fuel oil.
Russian virgin fuel oil D6 is a type of residual fuel, mainly used in power plants and larger ships. It is not possible to use it in smaller engines or vessels / vehicles where it is not possible to pre–heat it. D6 is its name in the USA. In other parts of the world it has other names.