Very Low Sulfur Fuel Oil

Very Low Sulphur Fuel Oil is any marine fuel with a sulphur content at or below 0.50% m/m, satisfying the global limit that entered force on 1 January 2020 under MARPOL Annex VI Regulation 14. Unlike the well-characterised ISO 8217 grades of IFO, VLSFO is supplied as a blended product and its properties — density, viscosity, flashpoint, carbon residue, and compatibility index — can vary significantly between suppliers and ports. This variability has led to documented cases of cat-fine contamination, stability problems, and lubricity failures affecting fuel injection equipment. IMO MEPC resolutions and the 2020 guidelines circulated under MEPC.1/Circ.878 advise operators on procedures for managing VLSFO blends, including segregation from incompatible residual fuels and pre-use testing. Engineers are required to record bunker details and retain fuel oil samples under Regulation 18 of MARPOL Annex VI. Where a vessel switches between multiple VLSFO grades, compatibility testing using a spot test or laboratory analysis is strongly recommended before blending tank contents.