Fuel Oil Market Guide: VLSFO, HSFO and Marine Fuel Explained

What fuel oil is

Fuel oil is the heavy end of the refining barrel: residual product left after lighter fractions are removed, blended with cutter stock to meet viscosity and sulphur specifications. Its largest single use is as marine bunker fuel.

Two families dominate bunkering. VLSFO (very low sulphur fuel oil, max 0.50% sulphur) is the mainstream compliant grade. HSFO (high sulphur fuel oil, typically 3.5%) remains in demand for vessels fitted with exhaust gas cleaning systems.

Key grades

• VLSFO — 0.50% sulphur maximum, the default global compliant grade.
• HSFO 380 — high sulphur residual, used with scrubbers.
• ULSFO — 0.10% sulphur, for emission control areas.
• MGO and gas oil — distillate marine fuels, cleaner and more expensive.
• Alternative bunkers — LNG, methanol and biofuel blends, growing from a small base.

How fuel oil is priced

Delivered bunker prices combine a cargo benchmark, a hub-specific delivered premium, barge and delivery cost, and the supplier's credit and margin. The Hi-5 spread — the differential between VLSFO and HSFO — determines the payback period on scrubber investment and is watched closely by owners.

Bunkering hubs

A handful of hubs handle a disproportionate share of global volume, because they combine refining or import capacity, deep storage, a competitive barge fleet and vessel traffic already passing through. Hub choice affects both price and quality risk.

Quality assurance

Off-spec fuel can damage machinery and strand a vessel. Buyers protect themselves with representative sampling at the point of custody transfer, accredited laboratory testing, mass flow metering where available, and clear contractual claim procedures.

Regulation

Sulphur limits, emission control areas, and progressively tighter greenhouse gas intensity rules shape which fuels are viable on which routes. Compliance planning is now a commercial function, not just a technical one.