Lloyd’s Register Warns ISO-Compliant Marine Fuels Are Increasingly Causing Operational Issues

Lloyd’s Register (LR) has warned that marine fuels meeting ISO 8217 quality specifications are increasingly causing operational problems onboard vessels, highlighting the need for shipowners to look beyond routine compliance testing when assessing fuel quality.

According to LR’s latest Fuel Oil Bunker Analysis and Advisory Service (FOBAS) Fuel Quality Report for the first half of 2026, the marine fuel market continues to experience persistent quality concerns, with some of the most significant operational issues linked to fuels that comply with standard specifications but exhibit poor stability, compatibility or contain problematic blend components.

On-Spec Fuels Still Creating Operational Challenges

The report notes that while off-specification fuels remain a concern, an increasing number of operational incidents involve fuels that pass routine ISO 8217 testing but later cause problems during storage, handling and onboard use.

In several investigations carried out during March and April 2026, vessels reported operational issues after bunkering fuel at a major global bunkering hub.

Subsequent forensic analysis found elevated concentrations of Estonian shale oil in many of the fuel samples, with some blends containing an estimated 10-15% shale oil.

Although shale oil is recognised as an acceptable blend component under ISO 8217, LR’s investigations found that higher concentrations may contribute to fuel instability, leading to operational problems affecting filters, separators and fuel pumps.

Fuel Quality Variability Remains High

The FOBAS report indicates that fuel quality variability remained elevated throughout the first six months of 2026, suggesting that quality-related issues are becoming a persistent feature of the marine fuel supply chain rather than isolated incidents.

The most frequently identified fuel quality issues included:

• Sulphur content exceeding specification limits
• Excessive water content
• Poor fuel stability and sediment formation
• Elevated catalytic fines
• Sodium contamination
• Low flashpoint distillate fuels

According to LR, these findings reinforce the need for more comprehensive fuel assessment beyond standard laboratory compliance testing.

Biofuels Not the Main Source of Quality Problems

The report also examined the growing use of biofuel blends, particularly fuels containing Fatty Acid Methyl Ester (FAME).

While biofuel consumption continues to increase across the shipping industry, FOBAS found that FAME blends were not the primary source of reported fuel quality issues.

Where operational problems occurred, they were generally linked to the conventional Very Low Sulphur Fuel Oil (VLSFO) component rather than the biofuel content.

Focus Shifts from Compliance to Fuel Behaviour

LR concludes that as marine fuel formulations become increasingly diverse, effective fuel management will require greater emphasis on understanding fuel behaviour, including stability, compatibility and blend composition, rather than relying solely on pass-or-fail specification testing.

The report recommends combining routine fuel quality monitoring with forensic investigations when operational issues arise to better identify emerging risks and minimise disruptions.

Murray Kirkwood, Fuel Specialist Consultant, Lloyd’s Register, said:

“The findings from our latest report show that fuel quality risk is evolving. The challenge is no longer simply identifying fuels that fail specification. Increasingly, operators are encountering fuels that meet the required limits but still create operational difficulties once they are stored, handled and used onboard.

As fuel blending becomes more complex, the distinction that matters is increasingly not between on-spec and off-spec fuel, but between fuels that are operationally resilient and fuels that are operationally fragile. Understanding that difference is becoming essential for shipowners and operators.”