A new FOBAS report says compliant fuels can still create onboard issues. File Image / Pixabay

Marine fuels meeting ISO 8217 specifications may still cause operational challenges, despite passing routine quality tests, according to Lloyd’s Register (LR).

The findings are outlined in LR's latest Fuel Oil Bunker Analysis and Advisory Service (FOBAS) Fuel Quality Report for the first half of 2026.

According to the report, some of the most disruptive cases involved fuels that complied with ISO standards but suffered from poor stability or compatibility, or contained non-conventional blend components only identified through detailed forensic analysis.

FOBAS investigated several incidents in March and April involving vessels that bunkered fuel at a major bunkering hub.

The analysis found elevated concentrations of Estonian shale oil in many samples.

While shale oil is permitted under ISO 8217, LR said higher concentrations were linked to operational issues affecting filters, separators and fuel pumps.

The report also found off-specification fuel cases remained elevated during the first six months of the year, with recurring issues including high sulfur, excessive water, sediment, stability problems, catalytic fines, sodium contamination and low flash point distillates.

Biofuel blends, particularly those containing FAME, were not identified as a major source of fuel quality problems.

Where issues did occur, they were generally linked to the conventional VLSFO component rather than the biofuel content.

LR said the findings highlight the need for ship operators to look beyond routine specification testing and place greater emphasis on fuel stability, compatibility and overall fuel behaviour when managing bunker quality.

The report can be downloaded from here.