Marine fuels that meet ISO 8217 specifications and pass standard quality checks can still lead to operational difficulties on board, according to Lloyd’s Register (LR).
The warning comes from LR’s latest Fuel Oil Bunker Analysis and Advisory Service (FOBAS) Fuel Quality Report, covering the first half of 2026, as reported by Ship & Bunker.
Compliant Fuel, Real-World Problems
According to the report, some of the most disruptive fuel-related incidents involved products that technically complied with ISO standards but suffered from poor stability, compatibility issues, or contained non-conventional blend components that were only detected through detailed forensic testing.
FOBAS looked into several incidents that occurred in March and April, involving vessels that had bunkered fuel at a major bunkering hub. Ship & Bunker reports that the investigation found elevated concentrations of Estonian shale oil in numerous samples. While shale oil is permitted under ISO 8217, LR said that higher concentrations of the component were linked to operational issues affecting filters, separators and fuel pumps.
Off-Spec Cases Remain Elevated
The FOBAS report also noted that off-specification fuel cases stayed elevated throughout the first six months of 2026. Recurring problems included high sulfur content, excessive water and sediment, stability issues, catalytic fines, sodium contamination, and low flash point distillates, according to the report.
Notably, biofuel blends containing FAME were not flagged as a major driver of fuel quality problems. Where issues did arise in biofuel blends, LR attributed them primarily to the conventional VLSFO component of the blend rather than the biofuel content itself, Ship & Bunker reports.
LR’s Recommendation
Based on these findings, LR said operators should look beyond routine specification testing alone. The report emphasizes placing greater weight on fuel stability, compatibility and overall behaviour when assessing bunker quality, rather than relying solely on ISO 8217 compliance as a guarantee of trouble-free operation.
Does This Matter to You?
These findings carry practical weight for anyone involved in bunker fuel purchasing, quality assurance, or vessel machinery management. A fuel batch passing standard ISO 8217 testing does not necessarily rule out onboard complications such as clogged filters, separator issues, or fuel pump damage, particularly where non-conventional blend components like shale oil are present in higher concentrations.
The persistence of off-spec cases involving sodium contamination, catalytic fines and stability problems also underscores the value of retaining bunker samples and conducting supplementary analysis beyond basic compliance checks, especially when sourcing fuel from hubs where incidents have previously been reported.
Gulf Bunkering does not provide operational or security guidance. This article is for informational purposes only. Operators should consult flag state authorities, P&I clubs, and relevant advisories for decisions relating to transit planning.
Sources: Ship & Bunker
