Very low-sulphur fuel oil (VLSFO) global viscosity levels in the fourth quarter of 2025 rose by 18pc compared with the same quarter in 2024, and maintained its record high set in the third quarter of 2025.
VLSFO viscosity levels at 50°C (122°F) averaged 190 centistokes (cst) in the fourth quarter, according to the latest data from French classification society Bureau Veritas. VLSFO viscosity levels were the same in the third quarter of 2025, which was the highest since Bureau Veritas started compiling this data in 2020.
Skagen, Denmark, was the port with the highest average VLSFO viscosity at 346cst followed by Gothenburg, Sweden, at 315cst and Las Palmas, Spain, at 310cst, according to Bureau Veritas.
The top three ports with the lowest average VLSFO viscosity included Istanbul, Turkey, at 103cst, and two US ports: Houston, Texas, and New Orleans, Louisiana, at 110cst and 111cst, respectively.
Global viscosity levels for high-sulphur fuel oil (HSFO) ticked up by 1pc to 313 cst in the fourth quarter of 2025, the highest total for any quarter in 2025. The average viscosity in the fourth quarter of 2024 was 310 cst.
The three ports with the highest average HSFO viscosity were all in China: Shanghai at 363cst, Hong Kong at 357cst and Zhoushan at 351cst, according to Bureau Veritas. The ports with the lowest average HSFO viscosity were Piraeus, Greece, at 217cst, Cuxhaven, Germany, at 236cst and Long Beach, California, which totaled at 246cst.
Higher viscosity levels of a marine fuel used in a vessel will produce less wear and tear in a ship's engine.
