Virgin Oil D6, also known as residual fuel oil, is a petroleum product that is obtained from the refining process. It has a high density and a high viscosity, making it a suitable heavy fuel oil used in large marine engines and power plants that require high levels of energy. Virgin Oil D6 is produced from the residue left over after the lighter hydrocarbons, such as gasoline and diesel fuel, are removed from crude oil. It is a heavy, black viscous liquid that is resistant to flow. The product has a high sulfur content, typically between 2.5% and 4%, and a calorific value of approximately 38 MJ/kg.