What’s In A Name?
Most of the time, you don’t need to know much about the fuel your car uses.
Petrol or diesel?
That’s all you need to remember, although you would be surprised how many people get this wrong every year – misfuelling is a big problem.
However, there is a bit more to fuel than this, and even petrol comes in different types. We’ve produced a guide to the main types of fuel on offer in the UK – click on a link for more information:
- Premium unleaded petrol
- Super unleaded petrol
- LPG Autogas
- Biofuels (biodiesel and bioethanol)
Premium Unleaded (95 RON)
This is bog-standard unleaded petrol. Despite the name ‘premium’, it’s actually the standard petrol sold all over Europe.
95 RON refers to the octane level of the petrol. This is a measure of how much compression the fuel can tolerate before it ignites. We don’t want petrol to ignite when it’s under compression in the engine cylinder, we only want it to ignite with a spark from the spark plug. Igniting under compression (known as pinking) can damage engines.
Higher octane levels mean that the fuel will tolerate higher levels of compression before igniting. This is required for a small number of high performance engines, but in most cases does not affect modern cars.
Premium unleaded is suitable for almost all petrol engines. You should be safe to use it unless your car’s user manual specifically specifies that you should only use petrol with an octane rating higher than 95. Very few cars require this.
Premium unleaded fuel pumps are usually green. Check the label before you fill.
Super Unleaded (97/98 RON)
Super unleaded is the highest octane petrol that is widely available in the UK. A higher octane rating means that the fuel will tolerate greater compression (more pressure) before it ignites. Ignition under compression is known as pinking and can damage engines. We only want petrol to ignite when it receives a spark from the spark plug.
Some car engines – especially high performance Japanese cars – require the use of super unleaded, while performance cars like Porsches and Ferraris will also tend to use this fuel, although it may not strictly be required.
Super unleaded can be used in any petrol engine but will only provide a beneficial effect in a small minority of engines as most engines are not able to take advantage of the higher octane rating.
Premium Fuels – e.g. Shell V-Power, BP Ultimate
Several fuel manufacturers offer own-branded high performance fuels that claim to offer additional benefits in addition to a higher octane rating. The best known example of premium petrol in the UK is probably Shell V-Power Unleaded. V-Power Unleaded has an octane rating of 99RON, the highest available in the UK.
Shell say that V-Power Unleaded offers three benefits – improved lubrication, cleaning action and higher performance (for engines that can benefit) due to the high octane rating.
Two alternative premium fuels are BP Ultimate Unleaded and Total Excellium Unleaded. These claim to offer similar benefits to V-Power but are only rated at 97RON.
Premium super unleaded petrol fuels can be used in any petrol engine but only some drivers/cars will experience a noticeable improvement in fuel economy or performance.
Many garages only offer one type of diesel for cars. It may be labelled as ‘city diesel’ or ‘low sulphur diesel’, just plain ‘diesel’ or something else.
Whatever it’s called, it should be fine for any current diesel car or van.
Diesel fuel pumps are usually black. Check the label before you fill.
Premium Diesel Fuels
As with petrol, however, there are a few higher performance diesel fuels available. The main three available in the UK are Shell V-Power Diesel, BP Ultimate Diesel and Total Excellium Diesel.
Whether these are worthwhile for you is down to your testing and your vehicle. These fuels generally offer a higher cetane rating which means that when used, they should ignite and burn more quickly and efficiently. These fuels also include additional lubrication and cleaning agents to help keep your engine clean and remove existing deposits, something which can reduce performance on diesel engines.
LPG Autogas is an alternative to petrol. LPG stands for Liquefied Petroleum Gas. Petrol engines have to be specifically converted to run on LPG and have an additional tank fitted (a bit like a gas cylinder).
LPG is available at a reasonable number of UK garages and is much cheaper than petrol, although it does give poorer fuel consumption.
However, before you start thinking about converting your car to LPG, it is important to remember that LPG is only cheaper because the fuel duty (tax) on it is much lower than the duty on petrol.
LPG isn’t intrinsically cheaper, so if the government of the day decides to change the rate of duty on LPG, the cost could shoot up. LPG is good in London, however, as it makes you exempt from the London Congestion Charge.
What Are Biodiesel & Bioethanol?
Biodiesel and bioethanol are diesel and ethanol fuels that are made from plant crops, rather than oil. They work in approximately the same way as diesel and petrol (respectively) and can be used instead of these fuels on their own or blended with regular diesel and petrol.
Since the 15th April, 2008, a government policy called the Renewable Transport Fuel Obligation has required UK fuel suppliers to include a certain percentage of biofuels in the fuels they sell. For 2010/11, this figure is 3.5% and this target is planned to gradually increase to just over 5% over the next few years.
What this means for you and I is that the petrol and diesel we buy in the UK (and throughout the EU) now normally includes some biofuel. These fuels still confirm to the relevant British Standards for petrol and diesel and are accepted by car manufacturers – so they won’t cause problems with your car or with the warranty on new cars.
Using A Higher Percentage of Biofuel In Your Car
If you want to run a fuel with a greater percentage of biofuel, then you need to look at a specific biofuel product.
Before doing this, be aware that many car manufacturers do not support the use of these fuels in their cars. While they may work fine, using an unsupported biofuel is likely to invalidate your car’s warranty if any problems arise as a result.
For diesel vehicles in the UK, biodiesel is the most common substitute for regular, oil-based diesel. While there are biodiesel companies out there who make 100% biodiesel, this requires modifications to most cars for them to remain reliable so isn’t recommended for most casual users.
More practical is to use a fuel that is a mixture of diesel and biodiesel. Some regular garages are now selling such fuels. The fuel names normally include a number indicating the proportion of biodiesel that has been added to regular diesel to make the fuel.
For example, B30 would be 30% biodiesel, 70% regular diesel.
For petrol car drivers, the choices are even fewer – bioethanol is the chosen biofuel substitute for petrol but availability of ethanol-based fuels in the UK is very limited. If you do find one, it should have the same naming convention as biodiesel fuels – e.g. E30 would be a fuel containing 30% ethanol and 70% petrol.