Last updated: 1 September 2026
Marine Gas Oil, commonly abbreviated to MGO, is a distillate marine fuel used to power vessels ranging from workboats and fishing vessels to ferries, commercial ships and other marine craft.
It is widely used in marine diesel engines and auxiliary machinery because of its relatively clean-burning distillate characteristics and its ability to meet stringent marine-fuel requirements when supplied to the correct specification.
However, the terminology surrounding marine fuels can be confusing.
Marine Gas Oil, Marine Diesel Oil, low-sulphur fuel oil, distillate marine fuel and bunker fuel are not necessarily interchangeable terms, and the correct fuel depends on:
- the vessel and engine manufacturer’s requirements;
- the ISO marine-fuel grade required;
- the sulphur limit applying to the vessel’s operating area;
- flashpoint and other safety requirements; and
- any additional regulatory or operational requirements applying to the voyage.
This guide explains what Marine Gas Oil is, how it differs from other marine fuels, the current ISO 8217:2024 standard, sulphur limits under MARPOL Annex VI and the key considerations when buying, storing and handling MGO.
What is Marine Gas Oil?
Marine Gas Oil is a relatively light distillate marine fuel used in compression-ignition marine engines and other equipment aboard vessels.
Unlike traditional heavy fuel oils, which contain heavier residual components from the refining process, MGO is predominantly a distillate product.
This generally gives Marine Gas Oil characteristics such as:
- lower viscosity than residual marine fuels;
- relatively low levels of contaminants;
- easier handling without the extensive heating required by heavy residual fuels;
- good combustion characteristics; and
- availability in low-sulphur grades suitable for use in emissions-controlled waters.
The term MGO is widely used within the marine industry, but purchasers should not rely on the name alone when specifying fuel.
The appropriate ISO 8217 grade, sulphur limit and vessel requirements should always be confirmed when ordering.
What is Marine Gas Oil used for?
Marine Gas Oil can be used in a wide variety of vessels and marine applications.
Typical uses include fuel for:
- commercial ships;
- workboats;
- ferries;
- fishing vessels;
- harbour and port vessels;
- tugs;
- offshore support vessels;
- inland and coastal vessels;
- certain leisure and pleasure craft;
- auxiliary engines;
- onboard diesel generators; and
- boilers designed to operate on suitable distillate marine fuel.
MGO can be used both for propulsion and for generating electricity or heat aboard a vessel where the equipment is designed and approved for the fuel.
The precise fuel requirement should always be confirmed against the vessel and engine manufacturer’s specification.
Is Marine Gas Oil the same as diesel?
Marine Gas Oil is a diesel-type distillate fuel, but it should not automatically be described as identical to ordinary road diesel.
Different standards and regulatory requirements can apply.
Road diesel used in UK vehicles will normally be supplied to the BS EN 590 road-fuel specification.
Marine fuels are commonly specified under ISO 8217, which defines requirements for fuels used in marine diesel engines and boilers.
The current international marine-fuel standard is:
ISO 8217:2024
This is the seventh edition of ISO 8217 and replaced the previous 2017 edition in May 2024.
ISO 8217:2024 covers both distillate and residual marine fuels and now explicitly accommodates a broader range of petroleum, synthetic, renewable and FAME-containing fuel components.
So while MGO and road diesel are closely related middle-distillate fuels, the correct product should always be selected according to the required marine specification rather than assuming that any diesel fuel is interchangeable.
Marine Gas Oil vs Marine Diesel Oil: what’s the difference?
Marine Gas Oil — MGO — and Marine Diesel Oil — MDO — are often confused.
Both are terms used for marine diesel fuels, but traditionally there is an important distinction.
Marine Gas Oil – MGO
MGO generally refers to a clear and bright distillate marine fuel without residual fuel material.
Within marine-fuel terminology, MGO has historically been associated with ISO distillate grades such as DMA and related distillate categories.
Marine Diesel Oil – MDO
MDO is traditionally associated with a somewhat heavier marine distillate fuel that may contain traces of residual fuel components.
Historically this has been associated particularly with the ISO DMB category.
The difference is therefore more nuanced than saying MDO is simply “diesel for big ships” and MGO is “diesel for small ships”.
The actual fuel selected depends on:
- engine design;
- required viscosity;
- fuel-treatment system;
- sulphur requirement;
- manufacturer approval; and
- the specification agreed between purchaser and supplier.
For commercial purchasing, the safest approach is to specify the required ISO 8217 grade and sulphur level, rather than rely solely on the labels MGO or MDO.
What is ISO 8217?
ISO 8217 is the internationally recognised standard covering fuel specifications for marine diesel engines and boilers.
The latest version is:
ISO 8217:2024
published in May 2024.
It replaced ISO 8217:2017, which is now formally withdrawn.
The standard establishes requirements covering characteristics that can include:
- viscosity;
- density;
- flashpoint;
- sulphur content;
- ignition characteristics;
- cold-flow properties;
- water;
- contaminants;
- acidity;
- stability; and
- other fuel-quality parameters.
ISO 8217:2024 specifies seven categories of distillate marine fuel, including a category intended for certain emergency-engine applications.
It also covers multiple categories of residual marine fuels and accommodates fuels containing approved renewable, synthetic and FAME components.
For a vessel operator, ISO 8217 provides a recognised framework for agreeing what marine fuel is being purchased and what properties that fuel must meet.
What are the current sulphur limits for Marine Gas Oil?
The sulphur content permitted in fuel used by ships is primarily governed internationally through MARPOL Annex VI.
There are two important limits.
Outside a Sulphur Emission Control Area
The global maximum sulphur content of fuel oil used aboard ships is:
0.50% m/m
This global limit has applied since 1 January 2020.
Before 2020, the international limit had been 3.50%.
The change is often referred to as IMO 2020.
Inside a Sulphur Emission Control Area
Within designated SOx Emission Control Areas — ECAs — the maximum sulphur content is:
0.10% m/m
The stricter limit is intended to reduce emissions of sulphur oxides and particulate matter in areas particularly affected by shipping emissions.
Existing SOx ECAs include areas such as:
- the North Sea;
- the Baltic Sea;
- the North American ECA;
- the United States Caribbean Sea ECA; and
- the Mediterranean Sea.
The Mediterranean became a SOx Emission Control Area on 1 May 2025.
For UK and European marine operators, the 0.10% limit is therefore especially important because substantial areas of northern European waters fall within designated ECAs.
Does all Marine Gas Oil contain less than 0.10% sulphur?
No — the term Marine Gas Oil alone should not be used as proof of sulphur compliance.
MGO is commonly available in ultra-low-sulphur grades and is frequently used by vessels that need to meet the 0.10% ECA limit.
However, sulphur content should be part of the product specification and bunker documentation.
The operator needs to ensure that the fuel supplied satisfies:
- the sulphur limit applying to the vessel’s location;
- the engine’s technical requirements; and
- all other relevant regulatory requirements.
Always verify the sulphur specification of the actual product being supplied.
What does 0.10% sulphur MGO mean?
A specification of:
MGO 0.10% sulphur
means the fuel has a maximum sulphur content of 0.10% by mass.
This type of low-sulphur marine distillate is commonly used by vessels operating within designated SOx Emission Control Areas.
A 0.10% fuel can also be used outside an ECA, assuming the fuel meets the vessel’s other requirements.
The reverse is not necessarily true: fuel compliant with the global 0.50% sulphur limit may not be suitable for compliance when the vessel enters a 0.10% ECA.
Operators therefore need to plan fuel management around the vessel’s intended route.
What does IMO 2020 mean for Marine Gas Oil?
IMO 2020 substantially reduced the permitted sulphur content of marine fuel used outside ECAs.
From 1 January 2020, the global limit fell from 3.50% to 0.50% sulphur by mass.
Vessels can comply through different approaches, including using:
- compliant low-sulphur fuel oil;
- low-sulphur marine distillates such as appropriate MGO;
- alternative compliant fuels; or
- approved exhaust-gas cleaning systems in circumstances where the regulations allow.
MGO has therefore remained an important compliance option, particularly where operators favour a relatively straightforward distillate fuel.
What are Emission Control Areas?
Emission Control Areas are designated sea areas in which ships are subject to tighter emissions requirements under MARPOL Annex VI.
For sulphur oxides, ships operating within the relevant ECAs must use fuel with sulphur content no higher than 0.10% m/m, unless an approved equivalent compliance method applies.
The North Sea and Baltic Sea have long operated as SOx ECAs.
The Mediterranean joined them on 1 May 2025, when its 0.10% sulphur requirement came into effect.
The IMO has also designated further ECAs, meaning vessel operators should continue checking the regulatory requirements applying to the waters in which they operate.
The relevant ECA boundary and current MARPOL requirements should be confirmed when planning international voyages.
Is Marine Gas Oil cleaner than heavy fuel oil?
Marine Gas Oil generally contains fewer heavy residual components than traditional heavy fuel oil and is commonly available with very low sulphur content.
Using appropriately specified low-sulphur MGO can therefore significantly reduce sulphur oxide emissions compared with higher-sulphur residual fuels.
It can also offer operational advantages associated with a distillate product, such as easier handling and reduced need for fuel heating.
However, MGO remains a hydrocarbon fuel.
Burning fossil MGO still generates:
- carbon dioxide;
- nitrogen oxides;
- particulate emissions; and
- other combustion products.
It should therefore not be described as a zero-emission or renewable marine fuel.
Does Marine Gas Oil need to be heated?
One operational advantage of MGO is that it generally does not require the extensive heating needed to handle high-viscosity heavy residual fuel oils.
Traditional heavy fuel oils may require heating for:
- storage;
- transfer;
- purification; and
- injection.
MGO has a much lower viscosity.
However, lower viscosity can itself create operating considerations, particularly when a vessel changes from a heavier fuel to a distillate product.
Engine manufacturers may specify minimum viscosity requirements at the fuel-injection system.
Operators should therefore follow manufacturer procedures when changing fuel grade.
Can vessels switch between heavy fuel oil and MGO?
Yes, where the vessel and its fuel system are designed to do so.
Historically, many ships using heavier marine fuels switched to low-sulphur MGO before entering an ECA.
A fuel changeover needs to be managed carefully because the fuels can differ significantly in:
- viscosity;
- temperature;
- density;
- sulphur content; and
- compatibility characteristics.
Rapid temperature changes can affect fuel-system components, while contamination of low-sulphur fuel with higher-sulphur residues may create a compliance problem.
Fuel tanks, lines and changeover procedures therefore need to be managed according to the vessel’s technical and regulatory requirements.
Can you mix Marine Gas Oil with other marine fuels?
Fuel compatibility should never be assumed.
Even where two fuels individually meet specification, mixing them can potentially create:
- instability;
- sediment;
- sludge;
- filter blockage; or
- off-specification fuel.
For distillate MGO specifically, contamination with another fuel can also alter its sulphur level or other characteristics.
Where a vessel changes from one bunker fuel to another, operators should follow the engine manufacturer’s and fuel-management procedures and consider compatibility where appropriate.
What is the flashpoint of Marine Gas Oil?
Flashpoint is an important marine-fuel safety characteristic.
It is the lowest temperature at which vapour from a fuel can form an ignitable mixture with air under specified test conditions.
For most conventional marine fuel used aboard ships, SOLAS requirements generally require a flashpoint of not less than 60°C, subject to specific exceptions.
Importantly, new SOLAS requirements took effect on 1 January 2026 concerning confirmation of fuel-oil flashpoint.
Ships receiving oil fuel must now, prior to bunkering, be provided with a declaration signed and certified by the supplier’s representative confirming that the fuel conforms to the applicable flashpoint requirements.
This means flashpoint documentation has become an even more explicit part of marine-fuel supply and bunkering compliance in 2026.
What changed to marine fuel flashpoint rules in 2026?
From 1 January 2026, amendments to SOLAS Chapter II-2 introduced new requirements relating to fuel-oil flashpoint.
Before bunkering, the ship must be provided with a declaration from the fuel supplier’s representative confirming that the fuel supplied complies with the relevant flashpoint requirements.
The Maritime and Coastguard Agency confirms that these requirements became mandatory internationally and in the UK on the same date.
The change reinforces the importance of obtaining appropriate product and bunker documentation rather than treating MGO simply as a generic diesel fuel.
Is Marine Gas Oil flammable?
Marine Gas Oil is a combustible hydrocarbon fuel and must be handled appropriately.
Although its flashpoint is considerably higher than that of highly volatile fuels such as petrol, it can still present significant fire, spill and environmental hazards.
Safe handling procedures should include:
- preventing ignition sources near fuel handling operations;
- using suitable transfer equipment;
- checking hoses and connections;
- preventing overfilling;
- controlling static and spill risks;
- maintaining appropriate ventilation;
- using suitable personal protective equipment; and
- following the relevant vessel and port bunkering procedures.
The product Safety Data Sheet should always be consulted for the specific fuel supplied.
Do you need an SDS or MSDS for Marine Gas Oil?
Yes, appropriate safety information should be available.
The current term is generally Safety Data Sheet — SDS. “MSDS” or Material Safety Data Sheet is an older term that is still widely recognised.
SOLAS Chapter VI requires ships carrying MARPOL Annex I oil products, including marine fuel oils, to be provided with a material safety data sheet before the fuel is loaded or bunkered. UK Maritime and Coastguard Agency guidance confirms this requirement.
The SDS provides information including:
- hazards;
- composition;
- first aid;
- firefighting measures;
- spill procedures;
- handling and storage;
- personal protective equipment; and
- other safety information.
Always use the SDS applying to the actual product supplied.
How should Marine Gas Oil be stored?
MGO should be stored in suitable, maintained fuel tanks designed for the application.
Good fuel-management practice includes:
- keeping tanks clean and in good condition;
- preventing water ingress;
- monitoring for sediment and contamination;
- inspecting vents, valves and pipework;
- separating incompatible fuels where necessary;
- maintaining clear product identification;
- retaining relevant delivery and fuel-quality documentation; and
- routinely checking stored fuel where operational reliability is critical.
Water and microbial contamination can affect stored distillate fuels and create problems such as corrosion, sludge and filter blockage.
Fuel-condition monitoring becomes particularly important for vessels or standby systems where fuel may remain in storage for extended periods.
Does Marine Gas Oil go off?
Marine Gas Oil does not have a single fixed expiry date applicable in every storage situation.
Fuel condition depends heavily on:
- storage temperature;
- tank cleanliness;
- water contamination;
- microbial activity;
- exposure to air and moisture;
- fuel composition; and
- storage duration.
Fuel that will remain unused for long periods should be monitored rather than assumed to remain in specification indefinitely.
For safety-critical or commercial marine operations, periodic inspection and fuel testing may be appropriate.
What documentation should you receive with Marine Gas Oil?
Requirements will depend on the vessel and bunkering arrangement, but marine fuel supply can involve documentation including:
- bunker delivery documentation;
- fuel specification;
- sulphur content;
- quantity supplied;
- supplier information;
- Safety Data Sheet;
- fuel sample arrangements where required; and
- applicable flashpoint declarations.
Since 1 January 2026, the new SOLAS flashpoint confirmation requirements should also form part of relevant bunkering procedures.
Operators should ensure documentation meets the requirements applying to their vessel and voyage.
Is Marine Gas Oil the same as bunker fuel?
MGO is a type of bunker fuel, but bunker fuel is a much broader term.
“Bunkering” simply refers to supplying fuel for use aboard a vessel.
Marine bunker fuels can include:
- Marine Gas Oil;
- Marine Diesel Oil;
- very-low-sulphur fuel oil;
- residual fuel oils;
- LNG and other gaseous fuels;
- methanol;
- biofuel blends; and
- other approved alternative marine fuels.
So all MGO supplied to a vessel may be described as bunker fuel, but not all bunker fuel is MGO.
What is the difference between MGO and VLSFO?
MGO is generally a marine distillate fuel.
VLSFO — Very Low Sulphur Fuel Oil — is a broader industry term generally used for fuel with sulphur content no higher than 0.50%.
VLSFO products can have significantly different composition and properties from MGO and may include blended or residual components.
MGO is typically:
- lighter;
- lower in viscosity;
- distillate-based; and
- easier to handle without extensive heating.
VLSFO can be more economical for certain large vessels but can require different onboard fuel handling.
The right choice depends on engine compatibility, operating area, fuel-system design and commercial considerations.
Is MGO suitable for generators?
Marine Gas Oil can be used in suitable diesel generators and auxiliary engines.
ISO 8217 itself notes that marine-fuel specifications can also be applicable to stationary diesel engines of the same or similar type as those used for marine purposes.
However, this does not mean MGO is automatically the optimum fuel for every land-based generator.
For a non-marine application, the required fuel specification, duty treatment and equipment manufacturer’s recommendations should be checked separately.
The old assumption that MGO is simply a general-purpose agricultural or generator fuel should therefore be avoided.
Is Marine Gas Oil used in agriculture?
MGO is principally a marine fuel term.
Agricultural machinery more commonly uses fuels specified for agricultural and off-road applications, including qualifying red diesel where the current rebated-fuel rules allow it.
Although distillate fuels may share similar underlying characteristics, describing MGO as a normal agricultural tractor fuel creates unnecessary confusion between:
- technical fuel specification;
- marine terminology; and
- UK fuel-duty rules.
For agricultural applications, specify the fuel actually required by the equipment and the relevant UK tax rules rather than ordering Marine Gas Oil simply because it is diesel-based.
What should you check before ordering Marine Gas Oil?
Before arranging an MGO delivery, establish the precise requirement.
Useful information includes:
Required fuel specification
Confirm the ISO 8217 grade or other specification required by the vessel.
Sulphur limit
Establish whether the vessel will operate in a 0.10% SOx ECA or an area subject to the global 0.50% limit.
Engine compatibility
Check requirements specified by the engine or vessel manufacturer.
Quantity
Confirm the volume required and the safe available capacity of the receiving tanks.
Delivery location
Marine deliveries can involve additional logistical considerations around port, marina, quayside or waterside access.
Bunkering arrangements
Confirm connection requirements, transfer rates, access restrictions and any applicable port procedures.
Documentation
Make sure the required bunker, specification, safety and flashpoint documentation will be available.
Providing this information before delivery helps ensure the correct product is supplied.
Marine Gas Oil FAQs
What does MGO stand for?
MGO stands for Marine Gas Oil.
It is a commonly used term for a relatively light distillate marine fuel.
What colour is Marine Gas Oil?
Marine Gas Oil is typically described as clear and bright as a fuel category, although colour can vary and dyes or markers may be present depending on tax and regulatory requirements.
Colour alone should not be used to identify whether a fuel meets the required specification.
Is MGO diesel?
MGO is a diesel-type distillate marine fuel, but it should not automatically be treated as identical to BS EN 590 road diesel.
Marine fuels are commonly specified against ISO 8217.
What specification is MGO?
The current international marine-fuel specification is ISO 8217:2024.
The precise distillate category required should be agreed for the individual vessel.
Is ISO 8217:2017 still current?
No.
ISO 8217:2017 was withdrawn in May 2024 and replaced by ISO 8217:2024, Edition 7.
What is the maximum sulphur content for marine fuel?
Outside designated SOx ECAs, the MARPOL global limit is generally 0.50% m/m.
Inside a designated SOx ECA, the limit is 0.10% m/m unless an approved equivalent compliance method is used.
When did the Mediterranean 0.10% sulphur limit begin?
The Mediterranean Sea SOx ECA took effect on 1 May 2025.
Is MGO always 0.10% sulphur?
No.
Do not rely on the product name alone.
The sulphur limit of the supplied fuel should be confirmed against the product specification and bunker documentation.
Is Marine Gas Oil better than Marine Diesel Oil?
Neither is universally “better”.
The correct fuel depends on the vessel’s engine, fuel system, required specification, operating conditions and regulatory requirements.
Does MGO need heating?
Unlike heavy residual fuel oil, MGO generally does not require extensive heating for normal transfer and combustion.
However, its lower viscosity needs to be compatible with the engine and fuel-injection system.
What is the flashpoint requirement for MGO?
Conventional marine fuel oils will generally need to meet the SOLAS minimum flashpoint requirements applicable to the vessel, commonly not less than 60°C, subject to defined exceptions.
From 1 January 2026, new SOLAS requirements also require supplier confirmation of compliance with the applicable flashpoint requirement before bunkering.
Does MGO require an SDS?
Yes.
Appropriate Safety Data Sheet information should be available before bunkering marine fuel oil.
Marine Gas Oil supply from Compass Fuels
Compass Fuels supplies marine fuels for commercial marine operators requiring dependable fuel deliveries and clear product specifications.
Whether you require MGO for vessel propulsion, auxiliary engines or onboard generation, speak to our team about:
- required fuel specification;
- sulphur requirements;
- delivery quantity;
- delivery location; and
- required delivery schedule.
We can also discuss other marine-fuel requirements where MGO is not the appropriate product.
For a Marine Gas Oil quotation, contact Compass Fuels on 0330 128 9838 or request a quote online.
Marine-fuel requirements vary by vessel, engine, operating area and regulation. Vessel operators remain responsible for confirming that the fuel ordered meets their technical and statutory requirements.
