Class verification: Up to 2.17% fuel oil saving and 31% prolonged stability

ISO 8217:2024 formally expands the scope of marine fuels to include up to 100% FAME in permitted grades, acknowledging biofuels as a practical decarbonization pathway. However, CIMAC WG7 clearly emphasizes that meeting ISO limits alone does not guarantee operational suitability

CIMAC guidelines identify several systemic challenges associated with FAME‑containing fuels:

• Reduced net calorific value, directly affecting fuel consumption
• Increased oxidation susceptibility during storage, especially at elevated temperatures and oxygen exposure
• Higher solvency and detergency effects, increasing risk of tank sludge mobilization and filter blockage
• Stability and compatibility sensitivity when blended with paraffinic VLSFO components

These documented risks underpin the need for validated fuel treatment solutions, specification compliance alone does not address the resulting operational issues.

Fuel Economy validation (up to 2.17%) on B30 VLSFO

Wilhelmsen Ships Service conducted an industry leading benchmark evaluation of fuel treatment performance on B30 very low sulphur fuel oil (VLSFO), focusing on measurable fuel economy under real engine conditions.

The evaluation was conducted on a MAN 6S35ME‑B9 two‑stroke, electronically controlled marine engine, representative of modern low‑speed propulsion systems. Testing covered multiple steady‑state operating loads across the engine operating range.

Verification and data integrity:

• The engine evaluation was conducted as a controlled shop trial and verified under the supervision of China Classification Society from test preparation through execution and data validation.
• All instrumentation calibration, test execution, and data integrity checks were supervised and verified by China Classification Society.
• The controlled shop‑trial environment eliminated shipboard operational variability, ensuring repeatable, traceable, and defensible results.

Fuel samples from each test condition were analysed by a laboratory accredited by the China National Accreditation Service for Conformity Assessment, confirming compliance with ISO 8217:2024 and that additive treatment introduced no adverse fuel quality effects.  

Results summary:

• Specific fuel oil consumption reduction of 1.51% to 2.17% relative to the untreated baseline fuel.
• Weighted specific fuel oil consumption reduction of 1.31%, calculated in accordance with CB/T 3254.2-2013 and GB/T 6072.1-2008

Calculated savings on conventional VLSFO

Fuelpower Catalyst delivered a 6–7% cetane number increase validated by IP 541, supporting improved combustion efficiency consistent with the CCS‑witnessed SFOC reduction.

Certified under LR APC, Fuelpower Conditioner delivers up to 46% sludge removal, supporting clean fuel systems and uninterrupted fuel injection, which are critical for maintaining consistent combustion performance.

This level of class involvement gives the results practical weight as part of a CII strategy, including incorporation into SEEMP Part III.

Oxidation stability validation (~31% improvement) on B100 FAME biodiesel

Wilhelmsen initiated a structured evaluation program to investigate the performance of Dieselpower BioEnhancer for biodiesel applications. The reference fuel selected was B100 FAME biodiesel. Additive samples were supplied by Wilhelmsen and tested independently by Bureau Veritas laboratories to ensure objectivity and traceability

Test methodology:

Oxidation stability was assessed using EN 15751 (Rancimat), the method reference by ISO 8217:2024 for distillate FAME

Two biodiesel samples were prepared for comparative evaluation:

• Control sample: Non‑additised B100 biodiesel
• Treated sample: B100 biodiesel additised by Dieselpower BioEnhancer

To assess storage resilience, both samples were subjected to accelerated ageing for 12 weeks at 35°C, with increased air–fuel exposure to represent challenging onboard storage conditions

Results:

Initial oxidation stability: 15.1 hours

After 12‑week ageing:

• Additised B100: 8.5 hours (43.7% deterioration)
• Non‑additised B100: 6.5 hours (57.0% deterioration)

After ageing, the additised fuel maintained an oxidation stability value approximately 31% higher than the untreated fuel and remained above the EN 15751 minimum requirement of 8 hours, whereas the untreated sample measured 6.5 hours, falling below the EN 15751 minimum requirement and rendering the fuel out of specification.

Visual inspection showed clear discoloration and degradation in the non‑additised sample, while the additised fuel retained its original appearance throughout the ageing period.

*Important clarification:

This evaluation addresses fuel stability and storage protection ONLY and does not make any fuel saving claim.

1 standard, 2 Fuel Classes with proven outcomes.

Wilhelmsen Ships Service has demonstrated validated additive performance across both fuel classes where fatty acid methyl ester (FAME) is present:

Residual fuels (B30 VLSFO)
Verified fuel economy improvement under class‑supervised, controlled shop‑trial engine testing

Distillate fuels (B100 FAME)
Verified oxidation stability and extended storage resilience through independent laboratory evaluation

It is engineered, tested, and verified performance, aligned with ISO 8217:2024 and CIMAC guidance for modern marine fuels

Ready to try these on your vessel? Talk to your local Wilhelmsen technical rep or fill our enquiry form to get in touch!

If you'd like to find out more, download our flyer below: