With a week until the implementation of International Maritime Organization (IMO) rules that will slash the permitted level of sulfur in marine fuels, shippers appear to be favoring very low-sulfur fuel oil (VLSFO) mixes over distillate fuels.

The price differential between VLSFO and marine gasoil has narrowed sharply at various major port locations around the world in recent weeks.

The IMO 2020 rules lower the ceiling on sulfur in ship fuel to 0.5% sulfur unless they are equipped with exhaust-cleaning systems known as scrubbers, down from 3.5% currently.

In Singapore, the world’s largest bunkering port, the difference in price between VLSFO and marine gasoil…