We're local, we're best, we're CPS.

Domestic 01953 713950

Commercial 01953 713540

Gas Oil

What is Gas Oil & what does it do?

Gas oil is surrounded by a lot of confusion due to its different names, recent changes in product specification and controlled use. Is it illegal to use?
Is it the same as regular diesel? Can it be used all year round?
We answer these and many more questions below.

Gas Oil and the CPS Fuels guide to Red Diesel use.

Gas oil which is also commonly referred to as red diesel, is a red dyed diesel fuel. If you’ve ever heard people call it red diesel, the name is more descriptive and becomes obvious when you see the cherry red colour of the fuel.

However, with many people still referring to it as gas oil, it is understandable that many would not have made the connection between the fuels’ two names. Most people have never heard of Gas Oil or Red Diesel unless they have worked in the construction or agricultural industries or worked on machinery that is powered by, or burns, gas oil.

Gas oil is the same fuel as white diesel which is used on public roads. White Diesel is available from all filling stations, where it appears on the petrol pumps as an option for cars, vans and HGV’s or lorries. Unlike the undyed white diesel, however, red diesel is strictly prohibited for use in ordinary road vehicles and significant fines will be enforced on anybody using it illegally. It is a “controlled oil” because of the rate of duty applied, the use of the dye to mark it, and the list of permitted or prohibited consumers.

CPS Fuels is a Registered Dealer in Controlled Oils (RDCO) who prides itself on offering a first class ordering and delivery service for Gas Oil and all other traditional, green, or controlled fuels. Whether it’s for a single 205-litre barrel, or a bulk order of 500 to 36,000 litres or more we are here to make it easy. You can call our commercial team on 01953 713540 or use our instant online quote facility.

If you are looking for a greener alternative to red diesel (gas oil) then give us a call to discuss your requirements. We have access to and the ability to supply green alternatives and carbon offsetting options to reduce your companies’ emissions and the impact it has on the environment around us.

Don’t order oil until you’ve spoken to us, we’re the fuel people you can trust.

Gas Oil  - the basics

Gas Oil or Red Diesel is a fuel used for power generation, in off-road vehicles, machinery and commercial boilers. It is cheaper than regular diesel due to a lower tax rate applied; however, it’s important not to use it in road-going vehicles as this is breaking the law and carries significant penalties.

In the UK, red diesel is commonly used by the construction or farming sectors and in hospitals or schools for heating or generators. It’s effectively the same as mineral diesel, it just has a red dye added so it can be spotted and identified when used illegally.

You must ensure you only use this product in applications approved by UK law. To provide an insight into its usage and to ensure you’re on the right side of the law, we’ve put together a FAQ, where this and other common questions are answered below:

Gas Oil / Red Diesel - FAQs & more detail

What is Gas Oil / Red Diesel?

Red diesel is a lower tax fuel than regular diesel that’s used widely throughout the UK. It has the same physical properties as regular diesel (except its colour, of course). Some key industries which use red diesel include farming, fishing and construction.

What is the tax on Gas Oil / Red Diesel?

The VAT (value-added tax) charged on red diesel is 5% up to 2,300 litres. This increases to the regular rate of 20% VAT above 2,300 litres; however, you may be able to claim 15% back if you are eligible for fuel duty relief. An example of this would be if you are using the fuel for horticultural produce, such as to help grow fruit, where you could be eligible to claim repayment. For more details on fuel duty relief, we advise you to check the Government’s website.

Why is there a red dye added to the fuel?

In the UK, Gas Oil / Red Diesel has a lower tax rate than regular (White) diesel. To help identify illegal usage in road-going or ineligible vehicles, a red dye is added to enable government bodies, HMRC and the Police to identify improper usage. It can easily be spotted in random checks and the user, driver and vehicle can be detained.

Can I use Gas Oil / Red Diesel in my car, van, truck or other motor vehicles?

Using red diesel in a vehicle on public roads is illegal in almost all cases. There are some exemptions from this law, however. Tractors are permitted to use gas oil to grit the roads during bad weather and can travel up to 1.5km on public roads to travel between sites that may be divided by public highways. Again we strongly recommend that you check the Government’s website for specifics for your own use case to ensure you are operating within the confinements of the law.

Why is using Gas Oil / Red Diesel in my motor vehicle illegal?

Red diesel is cheaper than regular diesel due to a lower fuel duty applied. The fuel is intended for commercial use where the business is involved in “off road” industries such as agriculture, construction and marine activities. The lower duty rate reduces the cost of fuel for them and so aids the economics of the business sectors they work in. If you use red diesel incorrectly, you are not paying the correct tax and you will be breaking the law.

We advise people to be absolutely sure they are eligible to use red diesel and ensure they have the correct supporting documentation if challenged.

What is Gas Oil / Red Diesel commonly used for?

Red diesel is the same fuel as regular diesel, so any vehicles, equipment and machinery that can be powered on DERV can also run on red diesel, as long as it’s within the law.

Some common uses include powering generators, machinery, commercial boats, off-road vehicles and commercial heating applications. We have a wide range of customers across the UK who purchase red diesel, including milk bottling factories, dairy farms, schools, hospitals and construction companies to name a few.

Can Gas Oil / Red Diesel be used as heating oil?

Yes, lots of people use red diesel as a heating oil. However Burnbright 35 our refined, not blended, industrial heating oil (IHO) is a lower priced, easy drop-in alternative, with an array of added benefits. Burnbright 35 performs as a gas oil, without carrying the duty burden, and it is widely used in commercial boilers, dryers and heaters across East Anglia as it preserves heat output and burner performance.

How much Gas Oil / Red Diesel does the UK use?

In 2017, it was reported that 15% of total diesel use in the UK was red diesel. This accounts for around £2.4 billion a year in tax reductions vs if the diesel was charged at the main rate.

What alternatives to Gas Oil / Red Diesel can CPS Fuels offer ?

Depending on use and the industry sector CPS Fuels can currently offer three alternatives.

Burnbright 35 is our refined, not blended, Industrial Heating Oil (IHO) and is specifically designed for commercial heating applications. It carries zero duty and can be used as an easy drop-in replacement for red diesel that can save your business money on drying and space and water heating.

Carbon Offset Gas Oil / Red Diesel is offered at a slightly higher price but comes with the benefit of reducing your carbon footprint and investing in green initiatives world.

HVO is a clean-burning fuel produced from certified green feedstocks which can be used as a drop-in replacement for red diesel and regular diesel. HVO fuel can reduce greenhouse gas emissions by up to 90% and has a shelf life of up to 10 years.

Why is Gas Oil / Red Diesel cheaper than white diesel?

Fuel can be a significant cost for many business sectors such as farming, fishing vessels, construction and forestry. The government lowered the duty on red diesel to support some of these industries.

What colour is Gas Oil / Red Diesel ?

As its name suggests, red diesel is red due to a dye that’s added to identify illegal use. Regular diesel appears clear with a faint yellow so is known as white diesel.

Does Gas Oil / Red Diesel have any more names?

Red diesel is also known as tractor diesel, farm fuel, 35-second oil, medium diesel, agricultural diesel, marine diesel, generator diesel, gas oil, BS 2869, or cherry red.

What happens if I put Gas Oil / Red Diesel in my car by accident?

Gas oil is not intended for use on public roads, so you will be breaking the law if you put it in your car. To avoid prosecution and a hefty fine, you must contact HMRC right away. The red dye is designed so it’s almost impossible to remove all evidence from a fuel tank, so if it’s tested, it will show you have been using red diesel straight away

If you do accidentally put red diesel in your car, you may be able to pay the duty that you should have paid on regular diesel, where you will be given a receipt so you can provide proof that you’re within the law.

Ideally, don’t put red diesel in your road vehicle in the first place if you can help it!

I have surplus Gas Oil / Red Diesel – what can I do with it?

If you have more than 2,000 litres of gas oil, you can take advantage of our fuel uplift service. If the fuel is in good condition, it’s possible that we can even pay you for it. If it’s degraded in quality, we can assist and ensure that it is lifted, removed and dispose of safely.

If you have smaller amounts you need to dispose of, we would advise you to use a recycling company or possibly contact your local council recycling centre to find out what options are available to you locally. 

How do I dispose of Gas Oil / Red Diesel safely?

Our fuel uplift service provided by our tank engineering team is a safe and environmentally-friendly operation. Our engineers will come to your site and uplift and dispose of your red diesel for you, saving you the hassle of having surplus fuels on-site.

If you need to dispose of a small amount of red diesel which is no longer usable, your local recycling centre could offer some advice.

How is Gas Oil / Red Diesel made?

Diesel is made through a refining process where crude oil is pumped out of the ground to produce a thick, black liquid. Through distillation, crude oil is split into a variety of fuels, one of which is diesel. To make diesel red the refiner or importer adds a red marker dye to the white diesel.

What does the red dye do to an engine?

Red diesel is as safe to use in engines as regular diesel, however it’s important to ensure that you invest in regular tank inspections as white and red diesel are both at risk from contamination over time.

Gas Oil / Red Diesel  Laws, Rules & Tax:

Do I need a licence to buy Gas Oil / Red Diesel fuel?

You don’t need a licence to purchase red diesel fuel, but when you order we will require you to answer questions so we can complete and record the information for HMRC under the RDCO scheme. This is to check and confirm that you intend to use it legitimately. We must report all sales of controlled oil and are obliged to pass on all information about your red diesel purchase to HMRC if they suspect illegal usage. More information on RDCO reporting can be found here on the governments’ website.

Is Gas Oil / Red Diesel tax-free?

Red diesel has a lower tax than regular diesel, but it’s still a heavily rebated fuel, meaning the tax applied is much lower than other fuels for off-road use. In most cases, it carries a 5% tax rate. Please view the governments’ website for more information or contact us directly if you have a query.

Is it illegal to use Gas Oil / Red Diesel?

It is illegal to use gas oil in road-going vehicles and it’s considered a tax evasion to do so. As already mentioned the fines and penalties for breaking the law are large. Red diesel is legal for use in off-road vehicles, machinery and commercial boilers.

Can I remove the red dye from Gas Oil / Red Diesel?

Removing the dye from red diesel is illegal. It’s incredibly hard to remove and any attempt to do so is known as fuel laundering which when proven carries prison sentences.

How do you get the tax back from Gas Oil / Red Diesel?

When purchasing red diesel, the rate you pay may depend on what you’re using it for and in what quantities. To apply to get the tax back on fuel you have purchased, you can fill in the HO27 form.

What is the penalty for using Gas Oil / Red Diesel illegally?

There is no fixed fine or penalty for using red diesel illegally. However, if caught, HMRC can charge you for:

  • Moving, storing and releasing your impounded vehicle/s.
  • Fuel duty not paid.
  • Restoration of your vehicle’s system
  • Cleaning of your tank & filters
  • A fee for removal of the red diesel
  • The difference between red and white diesel for the duration that they believe you have been illegally using red diesel for.

Repeat offences can result in considerable further escalation of costs and potentially could result in prison sentencing.

Needless to say, using red diesel illegally can be a very costly mistake to make.

How to report the misuse of Gas Oil / Red Diesel?

If you suspect that someone is illegally using red diesel, you can report them to the HMRC fraud hotline.

Who checks for Gas Oil / Red Diesel usage?

HMRC and the police check for illegal red diesel use by carrying out random spot checks using a dipstick test. The chemical dye added to the fuel is designed to linger in a tank and is impossible to remove, so if red diesel has been used in the past, you could be caught years down the line.

Gas Oil / Red Diesel Usage:

Which vehicles can use Gas Oil / Red Diesel?

All diesel engines can run on red diesel; however, it should only be used for commercial applications such as generators, boilers and tractors. For example, using gas oil in a vehicle on public roads is illegal.

The government’s website lists “excepted vehicles” that are permitted to run on red diesel, including:

  • Unlicensed vehicles not in use on public roads
  • Tractors
  • Light agricultural vehicles
  • Agricultural material handlers
  • Agricultural engines
  • Agricultural processing vehicles
  • Mowing machines
  • Snow clearing vehicles
  • Gritters
  • Mobile cranes
  • Mobile pumping vehicles
  • Digging machines
  • Road rollers
  • Tar sprayers

Please note, even though your vehicle is listed above, you still need to ensure its use is within the law. For example, when using red diesel in a tractor, you are welcome to do so for agricultural purposes, including travelling to and from different places of work, as long as they are within 1.5km of each other. Any further distance and you will be breaking the law.

Who uses Gas Oil / Red Diesel?

Red diesel is widely used throughout the UK in a variety of industries, such as farming, construction, data centres, events, hospitals, schools and backup generators.

One example is farmers who have a small farm and use agricultural vehicles such as a quad bike. If you only use a very small amount, a red diesel 205-litre barrel is a perfect solution as it can save you money over buying regular diesel and you only need to order a small amount.

Another example is a larger farm with grain dryers, a dairy and milk bottling plant & large tractors which all use red diesel. In this case, you would have one or more large tank(s) on the farm and take deliveries of up to 36,000 litres on a regular basis.

Can you use Gas Oil / Red Diesel for gritting roads?

Previously, only purpose-built gritters were allowed to run on red diesel when gritting public roads. However, as highway authorities generally have to concentrate on priority routes and are unable to reach rural roads in some cases they encourage farmers to use tractors on other routes. Tractors are the perfect solution for accessing remote and hard to reach areas to ensure the safety of communities but farmers were expected to refill their tractors with white diesel which was impractical when having to respond quickly to local gritting needs.

Today, there are 3 categories of agricultural vehicles that are permitted to use red diesel to grit roads:

1) Tractors

2) Light agricultural vehicles

3) Agricultural material handlers

How do you store Gas Oil / Red Diesel?

There are many options to store red diesel, depending on how much you use. For small users of red diesel, our 205-litre barrels with a spill kit and drip tray can be a simple and low-cost solution, with the added benefit of flexibility.

For large users of red diesel, the most cost-effective solution is to install an onsite oil tank to bunker vehicles or feed plant so allowing you to take advantage of bulk buying. We (AOTS link for We) can supply fuel tanks in a range of sizes from 500 litres to 120,000 litres to OFTEC standards. When storing oil on-site you must ensure you conform to oil storage regulations,

How do you store Gas Oil / Red Diesel on a farm safely?

A bunded tank is the most common solution and is required by law if you are storing more than 200 litres of red diesel. CPS Fuels will conduct safety checks pre delivery to ensure your fuel storage is safe to deliver to. We can also provide advice on tank security, replacement and oil storage regulations.


Can I use Gas Oil / Red Diesel for my backup generator?

Yes, gas oil is commonly used in backup power generators, as it is an efficient and low-cost fuel.

When relying on red diesel for backup emergency fuel, it’s important to invest in regular fuel tests and tank inspections to check for any signs of contamination. Over time, red diesel can degrade in quality due to the FAME content in it and this can eventually lead to fuel pump or filter issues which could result in the backup generator not kicking in when needed most. CPS Fuels can advise on ways to manage you fuel supply, stock and storage facilities so that the high quality of the fuel we supply is maintained for as long a period as possible. We offer a range of stability and storage additives to assist.

An increasingly popular alternative to red diesel for backup generators is HVO (internal product page link need) due to its vastly increased shelf life (up to 10 years). HVO is a synthetic diesel that has no FAME (link to CPS news article) and sulphur content which means it’s at less risk of contamination. Please note, it’s still important to invest in a regular fuel and tank management regime including inspections and testing to secure the reliability of your backup system.

Can I use Gas Oil / Red Diesel in a boat?

Yes, but this is an increasingly complex question and it depends on if you are using it for pleasure purposes, or for a commercial application such as fishing.

Red diesel may be used for heating or power generation, but not for propulsion in a non-commercial craft. Boat owners are able to specify what % of the fuel purchased is intended for use for heating and power generation to ensure the owner pays the correct tax levy on their fuel.

We would advise you to check with the Government website for more information on using red diesel in your boat and you can also check the RYA (Royal Yachting Association) website for more information.

Can I use Gas Oil / Red Diesel in a pleasure craft?

You can use red diesel for heating and electricity generation on a pleasure craft, but you are are not eligible to use red diesel for propulsion under current legislation.

Can I use Gas Oil / Red Diesel in my car if I only drive it on my farm?

Yes, but only if you are using it for off-road farming-related activity. You must not use red diesel in a car that drives on or crosses a public road.

Are Gas Oil / Red Diesel and heating oil the same?

They are both distilled from crude oil, but they are not the same fuel.

Heating oil is also known as 28-second oil, in reference to how many seconds it takes the fuel to pass through a specific measured hole.

Red diesel is also referred to as 35-second fuel as it takes longer to pass through the same hole, so right away from these names, you know that the viscosity of red diesel is thicker than heating oil.

Can Gas Oil / Red Diesel be used instead of home heating oil?

This depends on what you’re using it for. You can if it is for heating or powering commercial machinery, but you should check with the manufacturer of your equipment to ensure it will not cause any damage, or if modifications might be required to the system set up. We can provide you with product data sheets to assist you here.

However we also offer our own industrial heating oil (IHO); Burnbright 35 as a more cost-effective alternative to Gas Oil. It is exclusive to CPS Fuels, refined to a consistent high standard rather than blended, and is a simple to use drop-in replacement that is an easy money saving option for your burner or boiler.

Can Gas Oil / Red Diesel be used instead of home heating oil?

As they are 35- and 28-second oils respectively, the burners would potentially need adjusting as it burns at a slightly different rate.
Even so if it’s specifically for heating a home, domestic heating oil (internal product page link need) is likely your best option, or Burnbright 35 (IHO) (internal product page link need) if it’s for commercial heating.

Is Gas Oil / Red Diesel bad for my car?

Red diesel won’t damage your car as it’s the same fuel as white diesel, just with a red dye added. There are very few circumstances where you would be able to put red diesel in a car though such as if your vehicle has done a SORN (Statutory Off-Road-Notification) – but even if you do this your fuel tank will be stained so if you ever want to remove the SORN from the car, you would run into issues when getting it back on the road legally.

Does Gas Oil / Red Diesel produce more smoke than regular diesel?

Assuming your red diesel is the same quality as white diesel, it should not produce any additional smoke than regular diesel.

Is Gas Oil / Red Diesel flammable?

Red diesel isn’t flammable, but it is combustible. Flammable fuels are classified as a liquid that has a flashpoint of less than 100°F/38°C, whereas combustible liquids have a flashpoint of more than 100°F/38°C. This is the temperature the liquid will evaporate enough to ignite. As red diesel has a minimum flashpoint of around 125°F/52°C, it is classed as a combustible.

Can Gas Oil / Red Diesel go off?

Red diesel will stay in good condition in a tank for up to a year. If you have any doubts about the quality of your fuel or the condition of your tank storing it then we suggest you get a trusted fuel expert like CPS Fuels to check it for you. The 1-year shelf life assumes that you are providing good storage and maintenance. It’s important to regularly check your tank is in the best possible condition to minimise the costly implications of contamination and tank corrosion.

At CPS Fuels, our tank specialists AOTS can offer the whole package: we can come to your site, test your red diesel, polish it and clean your tank – or alternatively, if it’s too badly contaminated, we can uplift it and provide a fresh supply of red diesel.

If you need a more reliable and environmentally-friendly fuel, consider HVO (internal product page link need)which has a much longer shelf life which could be up to 10 years if the tank is clean and managed.

How long does Gas Oil / Red Diesel last?

Gas Oil / Red Diesel lasts up to a year in a well-maintained storage tank.

Will Gas Oil / Red Diesel make my MOT fail?

If you have purchased a car which you suspect previously used red diesel, or you have ever accidentally used it this could be a valid concern. Garages won’t specifically check for red diesel, but it’s a little hard not to notice. A reputable garage will be extremely familiar with the colour of regular diesel, and if they see you have used red diesel it would be very likely they would report you to HMRC. If you have any doubts about your car having any remnants of red diesel from anything at all, consult your local garage about replacing your fuel tank, or replacing your car!

What else can we help with?

Whether it’s a single 205-litre barrel, IBC, or a bulk order of 500 to 36,000 litres or more, we are here to make it easy.

Contact Us

CPS Fuels can offer alternative fuels and green product solutions for on buildings, heating, on road, off road and static engines along with other diesel powered plant and machinery.

If you are unsure of what product you require, need information, options, assistance or prices, then call our Commercial Team on 01953 713540

Don't order oil 'til you've spoken to us.