International bunker trading firm Integr8 Fuels on Monday (7 July) shared its new report ‘Mediterranean ECA: Immediate Operational and Commercial Impact of Implementation’ which provides the first comprehensive analysis of the rule’s effects on fuel quality and regional availability.

The data reveals a market in rapid transition, confirming some industry predictions while uncovering new, emerging risks for ship operators. The following key findings include:

1. Dramatic Supply Shift Confirmed: VLSFO Availability Contracts Sharply. VLSFO’s share of the Mediterranean fuel market has plummeted from over 60% in December to just 37.5% in May. In parallel, the number of ports supplying VLSFO has fallen by 47%, creating new logistical challenges for vessels that continue to use the grade.
2. VLSFO Instability Spikes as Supply Chain Adapts. Very Low Sulphur Fuel Oil (VLSFO) off specification rates more than doubled from 1.5% in December to 3.8% in May. Critically, one in four (25%) of these off-specs were for total sediment potential (TSP), indicating a rising risk of sludge formation that can damage engines. This trend appears linked to extended in-tank storage and the consolidation of older fuel stocks as demand slows and suppliers pivot away from VLSFO.
3. Persistent Flash Point Risks in Key LSMGO Hubs. Flash point non-conformance has increased significantly and now accounts for over two-thirds of all LSMGO off specs. Our data shows this is not a random problem, with over 75% of all flash point incidents concentrated in Spain, Turkey, and Italy, signalling a persistent potential for SOLAS violations in core supply zones.

Note: The full report may be obtained from Integr8 Fuels here.

Photo credit: Integr8 Fuels
Published: 8 July 2025

Stanley George, Group Science & Technical Manager of marine fuels testing company VPS, on Monday (23 June) highlighted engines operating on FAME-based biofuels are more susceptible to rapid oil viscosity degradation, where FAME does not evaporate easily, leading to cumulative effects:

Engines running on Bio-blends containing Fatty Acid Methyl Esters (FAME), especially pure FAME, e.g. 100% FAME can experience decreased engine oil viscosity over time.

Fuel oil contamination in engine lubricants is a known phenomenon, and most marine-grade engine oils are formulated to tolerate certain levels of such contamination while maintaining operational performance.

The impact of FAME contamination is more pronounced in four-stroke trunk piston engines due to their design and operational characteristics. These engines use a common oil sump for both crankcase and cylinder lubrication, making them more vulnerable to fuel ingress through injector leaks or blow-by gases. Unlike two-stroke crosshead engines, which have separate lubrication systems that limit fuel-oil interaction, four-stroke engines continuously recirculate the same oil, allowing FAME (which has a high boiling point and low volatility), to accumulate over time. This leads to a more significant reduction in oil viscosity and faster degradation of lubricating properties.

A typical SAE (Society of Automotive Engineers) 30 grade engine oil has a viscosity of about 90 to 110 cSt at 40°C and a B100 (100% FAME) or its fossil counterpart such as DMA (distillate fuel) has a viscosity in the range of 4 cSt at 40°C. Any contamination of the fuel (distillate or Bio distillate blends contain FAME) into the used engine oil can therefore significantly reduce the viscosity of the used engine oil.

Most OEMs specify both minimum and maximum viscosity limits for engine oils, beyond which the engine must not be operated to avoid wear or lubrication failure. For example, a common condemning limit is a 25% reduction in viscosity at 40°C from the fresh oil value. In the case of an SAE 30 grade oil (with a typical fresh viscosity of around 90 cSt at 40°C), this corresponds to a minimum allowable limit of approximately 67 cSt.

When comparing the viscosities of distillate fuel and B100, there is no significant difference (both typically range between 3 to 5 cSt at 40°C). However, a noticeable drop in engine oil viscosity is not usually observed when engines operate on conventional distillate fuel. This is likely due to the higher volatility and lighter fractions present in fossil fuels, which tend to evaporate over time. Additionally, the routine top-up of fresh oil during engine operation, needed to compensate for losses from evaporation and leakage, helps maintain a more stable overall oil viscosity. As a result, the dilution effect is minimised, and the lubricating oil retains its properties for a longer duration compared to operation on B100.

Distillation Behaviour Analysis of FAME

ISO 3405 is an international standard that outlines a laboratory method for determining the distillation characteristics of petroleum and related products at atmospheric pressure. This tests helps us to understand the composition and behaviour of fuel during storage and use including the tendency to form vapours.

Typically in this method, the sample is distilled under controlled conditions. Throughout the distillation, the temperature at which specific volumes of the sample evaporate is recorded. Key measurements include, Initial Boiling Point (IBP) -Temperature at which the first drop of condensate is collected, Final Boiling Point (FBP) -Temperature at which the last drop of liquid evaporates and temperature at Specific Recovery Percentages, temperatures corresponding to 10%, 50%, and 90% volume recovery, among others. The collected data is used to construct a distillation curve, which illustrates the boiling behaviour of the sample.

In order to understand this phenomenon we compared the distillation characteristic of a 100% FAME (B100), 30% FAME (B30) and pure straight run distillate fuel using the ISO 3405 method. Below is a graph illustrating the differences in the distillation characteristics.

Note: The full article by VPS can be viewed here. 

Photo credit: VPS
Published: 24 June, 2025

Steve Bee, Group Marketing and Strategic Projects Director of marine fuels testing company VPS, on Thursday (29 May) explored if the greater demand for marine gas oils/distillates would lead to poorer fuel quality following the recent implementation of the new Mediterranean ECA, which is already witnessing an increasing demand for marine distillates to satisfy the 0.10% Sulphur limit. 

He also discussed the fuel management concerns and challenges associated with such marine fuels:

Introduction to Distillate Fuels

With the recent implementation on 1st May 2025, of a new Emission Control Area (ECA) in the Mediterranean Sea, the question arises, will we see an increase in demand for marine gas oils/distillates? If so, will a higher demand result in a lower quality product? This article looks to address current marine distillate quality and the test parameters which can be employed to assist in determining fuel quality and the relevant fuel management considerations, required to mitigate any associated risks through the following:

1. Density
2. Viscosity
3. Flash Point
4. Cold-Flow Properties
5. Lubricity
6. FAME
7. Microbial Activity
8. Incompatibility

For decades global shipping has thought of distillate fuels, as problem-free fuels. Yet whilst High Sulphur Residual Fuels and Very Low Sulphur Fuels, offer certain fuel management challenges, marine distillate fuels, are not exempt, they simply have different considerations and challenges.

Within the ISO8217:2024 marine fuel standard, there are four grades of fossil marine distillates, DMA, DMB, DMX, DMZ, plus three Fatty Acid Methyl Esters (FAME) containing distillates, DFA, DFB and DFZ, to support decarbonization compliance.

Today, DMA is the most commonly used marine distillate. Suitable for most marine engines, DMA is known for its cleaner combustion, consistent performance, and ability to reduce emissions when compared to heavier, residual marine fuels. This type of fuel is also commonly referred to as, Low-Sulphur Marine Gas Oil (LSMGO).

• DMA: This is the LSMGO highlighted above. As per its classification, it’s a standard marine distillate suitable for various marine engines.
• DMB: The heaviest fuel among the distillates and is typically used in medium-speed marine engines.
• DMX: Often referred to as a special light distillate, DMX is used primarily for emergency engines and equipment, plus some high-speed engines that require fuels with lower viscosity and density.
• DMZ: This is a clean distillate intended for use with more sensitive engines.

Ultra Low Sulphur Fuel Oil (ULSFO) is another similar fuel type. Marine fuels like DMA are often integrated with specific additive blends, these are designed to address and counter challenges typical of marine environments, for instance, microbial growth in storage tanks. DMA’s cetane number, which indicates the ignition quality of the fuel, usually surpasses 45, whilst ULSFO’s cetane number floats between 40 to 45. While there are premium diesel variants with a higher cetane number, the main objective of ULSFOs is to lower sulphur emissions.

The higher cost of DMA is another differentiating factor and can be swayed by marine-specific rules, the demand it witnesses in ports, and the overarching dynamics of the global marine fuel market. For ULSFO, its pricing hinges mainly on elements like crude oil prices, the capacity of refineries, transportation overheads, and the demand from the road transportation sector.

Marine Distillates (MGO) and ULSFOs account for 14.2% and 1.2% respectively, of all fuel samples sent to VPs for testing:

Whilst distillate deliveries remained stable in Q1-2025 at around 800,000mt, ULSFO deliveries have risen 15% quarter-overquarter.

Fuel Management Concerns relating to Marine Distillates

Minimising Financial Risks: Density Short-lifting – Fuel is delivered by volume but paid for by weight. Overstated density stated in a Bunker Delivery Note (BDN) results in operators paying for fuel that was not actually supplied. VPS data and vast experience indicates that short lifting of distillates significantly exceeds that of HSFO and VLSFO. This fact, together with the premium price of distillates can be a substantial drain on the operating budget of a company.

Currently 39% of MGO samples tested by VPS, fall below 850Kg/m3, where the ISO8217:2024 specification limit is 890Kg/m3.

The BDN values are predominantly higher, indicating such overstatements, result in lost fuel for the vessel.

Even without heating the fuel, a warm engine room can easily heat the fuel to e.g. 50°C. A fuel bunkered as 2cSt at 40°C, will have a viscosity of 1.7cSt at 50°C, below the required minimum 2cSt that is recommended by major engine, boiler and pump manufacturers.

Currently 99.1% of all MGO samples tested by VPS in Q1-2025, have a viscosity >2.0 CSt and less than 6.00 CSt.

Ensuring Compliance with Statutory Regulations: Low Flash Point – Flash point is the temperature at which the vapours of a fuel ignite when a test flame is applied. It is considered to be a useful indicator of the fire hazard associated with the storage of marine fuels. The Safety of Life at Sea (SOLAS) convention and ship classification society rules, require all fuels to have a flash point of more than 60°C, with the exception of Emergency Equipment (eg lifeboat engines). Yet, the Flash Point of marine distillates is an on-going issue. In 2024, the Flash Point cases relating to MGO fuels, accounted for 22% of the Bunker Alerts issued by VPS.

Poor Cold-Flow Properties: Poor cold flow properties, indicated through pour point (PP), cold filter plugging point (CFPP) and cloud point (CP), can lead paraffinic wax precipitation from the fuel. This wax can then lead to clogged filters and pipe lines and in the worst case, complete solidification of the fuels in vessel tanks if not heated sufficiently.

In Q1-2025 the average Pour Point of MGO dropped to -7°C:

Insufficient Fuel Lubricity: Marine engine fuel pumps are self-lubricated. If the lubricity of the distillate is poor, high wear may be caused usually within a short period of time. The risk of encountering poor lubricity is higher when sulphur is below 0.05% (500ppm). Therefore, in such cases testing the fuel for its lubricity level is a key requirement. This is undertaken via laboratory test method ISO12156-1, with a specification limit of 526µm Corrected Wear Scar Diameter.

Many people believe it is sulphur which actually provides the distillate with its natural lubricity. This is incorrect. The process to remove sulphur from fuel is termed, “hydrodesulphurization” and it is this process to remove sulphur which also removes polyaromatics present, which do provide the natural lubricity to fuels.

Fatty Acid Methyl Esters (FAME): It now seems ironic that prior to ISO8217:2010, FAME was seen as a contaminant if found within marine fuels. Then the 2010 revision, allowed “de-minimus” levels of FAME to be present in marine fuels. The ISO8217:2017 went a step further by including three new distillate grades, DFA, DFB and DFZ, with a FAME limit of 7% in each. Now the ISO8217:2024 allows up to 100% FAME in relation to marine biofuel blends.

Although FAME has good ignition, combustion and lubricity properties, as well as providing a reduction in GHG emissions, it can reduce oxidation stability and increase the risk of microbial growth. The risks increase if the fuel is to be stored for a prolonged period of time, e.g. more than 3 months.

Microbial Contamination: Bacteria, yeast and fungi can live and thrive in distillate fuel tanks in the presence of water and elevated temperatures. Such conditions provide an ideal environment for microbial growth. Such microbes, if allowed to grow can lead to operational issues such as clogged filters/nozzles and corrosion in fuel tanks and pipework. This situation can be further complicated by the presence of Fatty Acid Methyl Esters (FAME), which can provide a further source of nutrients for bugs to feed upon. To monitor this microbial activity it is recommended to carryout BYF-testing. Good onboard house-keeping, ensuring a water-free environment will reduce the risks of bug-growth. However, should the situation deteriorate, then biocides can be used to kill the microbes.

Incompatibility Issues: Loss of propulsion and/or fuel incompatibility during fuel change-over from HSFO or VLSFO to a distillate fuel when entering an emission control area (ECA) is another problem that ship operators should be aware of. Changing between residual-based fuels and distillate fuels can inevitably result in mixing in the fuel system. The result may be incompatible mixtures and in the worst case, a loss of propulsion.

Note: The full article by VPS can be read here. 

Photo credit: VPS
Published: 30 May, 2025