Fuel oil is a broad term that could refer to a number of different refined products ranging in density from kerosene to residual fuel oil. However, it typically refers to residual fuel oil or No. 6 fuel oil.
Grades of fuel oil used in US markets:
- No 1 - A fuel oil consisting of kerosene range material. Also called stove oil or range oil
- No 2 - A fuel oil consisting of light atmospheric gasoil material. This is the fuel oil used as a home heating oil. It is very similar to diesel but of lower quality. Typically, it has a lower cetane and higher sulfur content. Also called Bunker A
- No 3 - This is a now obsolete light gasoil range fuel oil, that has been combined with No 2
- No 4 - A fuel oil consisting of VGO range material, intended for commercial heating furnaces lacking a preheater
- No 5 - A fuel oil consisting of vac resid range material with a low viscosity, allowing it to be pumped without preheating. Also called Bunker B
- No 6 - A fuel oil consisting of vac resid range material with a high viscosity, requiring preheating before pumping. Also called residual fuel oil or Bunker C