D6 fuel, also known as residual fuel oil (RFO), is a type of fuel that’s used in power plants and large ships. It’s characterized by its high viscosity and high pollutant content, and it needs to be preheated before use:
Viscosity
D6 fuel has a high viscosity, so it can’t be used in smaller engines or vehicles that can’t be preheated.
Pollutants
D6 fuel contains high levels of pollutants, such as sulfur.
Preheating
D6 fuel needs to be preheated to a temperature of 220–260°F (104–127°C) before it can be used.
