D6 fuel

D6 is a type of residual fuel, mainly used in power plants and larger ships. The fuel is required to be preheated before it can be used. 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.

Number 6 fuel oil is a high-viscosity residual oil requiring preheating to 220 – 260 °F (104 – 127 °C).

Residual means the material remaining after the more valuable cuts of crude oil have boiled off. The residue may contain various undesirable impurities including 2 percent water and one-half percent mineral soil. D6 fuel is also known as residual fuel oil (RFO), by the Navy specification of Bunker C, or by the Pacific Specification of PS-400

D6 fuel is used mostly for generators.

The price of D6 diesel traditionally rises during colder months as demand for heating oil rises, which is refined in much the same way.

Because of recent changes in D6 fuel quality regulations, additional refining is required to remove sulphur, which contributes to a sometimes higher cost.

In many parts of the United States and throughout the United Kingdom and Australia, D6 diesel may be priced higher than petrol.

Reasons for higher-priced D6 diesel include the shutdown of some refineries in the Gulf of Mexico during hurricanes, diversion of mass refining capacity to gasoline production, and a recent transfer to ultra-low sulphur diesel (ULSD), which causes infrastructural complications.

In Sweden, a D6 diesel fuel designated as MK-1 (class 1 environmental diesel) is also being sold; this is a ULSD that also has a lower aromatics content, with a limit of 5%. This d6 fuel is slightly more expensive to produce than regular ULSD.

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