1. Fuel oil in futures trading, commonly known as heavy oil, is the residual heavy oil after gasoline and diesel oil are extracted from crude oil, which is characterized by large molecular weight and high viscosity. It is mainly used for external direct combustion of power generation boilers and heating boilers, so it is called "fuel oil". At present, heating boilers for central heating in many cities stop using coal as fuel and use natural gas or fuel oil as energy, which is due to the factors of reducing carbon dioxide emissions. However, it is not the combustion mode of liquid oil that we usually think, but the oil is atomized through a high-pressure nozzle and burned in a combustion chamber to make the combustion full.

The fuel oil standard of Shanghai Futures Exchange is 180 heavy oil, and the national standard code is 180CST.

2. Commonly known as heavy oil, it is gutter oil. After crude oil is refined into diesel gasoline and other oils, the remaining oil with more impurities is used to burn boilers and ships, which is of course much cheaper than gasoline.