Ship fuel oil: Both 120 and 180 are viscosity grades of heavy oil for ships (IFO), referring to a 50 ℃ kinematic viscosity not exceeding 120 cSt and 180 cSt, respectively; 120 has better liquidity and lower system load, while 180 has higher energy density but requires higher preheating and more precise processing systems.

120: It is more load friendly to the system, has lower maintenance costs, and is suitable for old/small ships or working conditions with simpler requirements for preheating and filtration.

180: Higher energy density and better procurement cost, suitable for fixed speed navigation of large low-speed engines, requiring more complete heating, filtering, and separation systems.