Is All Petrol & Diesel The Same?

Filling up car with fuelIt’s a common question that often triggers big arguments.

Is branded petrol and diesel better than supermarket fuel, or should you just buy the cheapest you can find?

The problem is that most people don’t know how the fuel business works, and the truth is a well-kept trade secret. Let me explain.

The Easy Bit – Premium Fuels (Shell V-Power, BP Ultimate, etc.)

We’ll start with the easy bit.

Premium fuels, such as Shell V-Power Nitro+ and BP Ultimate, are not the same as regular petrol or diesel , although you can mix them freely with standard fuels without problems. Petrol like this is known as ‘super unleaded’.

Confusingly, the petrol that is labelled as ‘premium unleaded’ on forecourt pumps (e.g. Shell Fuelsave) is actually standard petrol. When it comes to fuel, super is better than premium!

These ‘super unleaded’ fuels cost several pence per litre more than regular unleaded. For this extra money, you get a different, more sophisticated package of additives for cleaning and lubrication, and fuel with a higher octane rating.

It’s a similar story with ‘super’ diesels, like BP Ultimate Diesel.

Octane (petrol) and cetane (diesel) ratings describe the way a fuel burns inside an engine. Broadly speaking, a higher rating means a fuel will burn more efficiently and effectively inside your engine. This may improve performance and/or economy slightly – although not all drivers will see a noticeable difference.

Some supermarkets also offer their own super unleaded — notably Tesco, which offers Tesco Momentum 99 octane. This is usually cheaper than Shell V-Power or BP Ultimate, but opinions vary as to whether it provides the same engine cleaning and mpg improvements as the top two fuels.

Another point is that Tesco Momentum 99 super unleaded reportedly contains more ethanol than super unleaded fuels like BP Ultimate. This provides an octane boost but some people believe it doesn’t provide the same efficiency gains as the more expensive branded fuels.

Like everything to do with fuel, people have different opinions, and the facts are hard to find.

Standard Unleaded and Diesel Fuels

The big debate is over whether the standard petrol and diesel sold by supermarkets is the same quality as that sold by branded fuel companies like Shell, BP, Esso and Total.

Let’s start with some known facts:

All fuels sold in the UK conform to the relevant British Standards. This means that they should all work in roughly the same way and you can mix them freely in your car’s fuel tank.

The standard petrol and diesel that’s sold on garage forecourts is mixture of two things:

  • ‘Base’ fuel
  • An additive package

The base fuel is the same for all companies – in fact, it usually comes from the same tanks at the local fuel refinery/distribution centre. What varies is the additives package that goes into the fuel. These additives packages are secret recipes of extra ingredients that help keep the engine clean and improve lubrication inside the engine cylinders.

Each fuel company has its own additives packages and these are different. So it is possible (but not common) for some drivers to feel that their car responds better to the additives used by one fuel manufacturer over those of another.

What About Supermarket Fuels?

There are all sorts of stories that go round about supermarket fuels, but the fact is that supermarket fuel tanker lorries are often seen filling up from the same tanks as branded fuel lorries (e.g. Shell, BP) – so the chances are that most of the time, the fuel they sell is the same, although again, it may have different additives packages.

However, one common story about supermarket fuel is that some supermarkets don’t have a regular fuel supplier. Instead, they buy odd lots of fuel from wherever it’s cheapest, including abroad. This could (if it happened) lead to supermarket fuel having a more variable set of additives than branded fuels.

Not many people really know the truth about this business, and they are not the kind of people who will reveal all on the internet. Unfortunately, that means we will have to keep guessing as to whether there is any meaningful difference between supermarket fuels and branded fuels.

As you can see from the many comments below, many drivers have strong (and opposing) views on this subject! Feel free to join in the conversation.

164 thoughts on “Is All Petrol & Diesel The Same?

  • April 11, 2018 at 5:45 am

    There’s a lot more to engine reliability and performance than fuels and additives. You can put Shell this and BP that into your car but if you’ve not serviced it for years then the performance will suffer. My new focus Derv runs great on Tesco fuel, I asked Ford if a particular brand of fuel was preferred and the sales manager said ‘We can’t tell what brand you use so it has no effect on your warranty’. In 2 years when the warranty expires, the car goes back and I get a new one. My old M3 got the very best Petrol and the very best service. It was fantastic and completely dependable.

    So all I’m saying is, If your putting expensive fuel in your car expecting a better return. Have it serviced regularly and with quality oils and parts and it most likely will.

  • May 2, 2018 at 8:58 am

    I have compared many different fuel garages and found that Tesco was the worst for the amount of mpg and esso and Texaco are the best. Sainsbury’s isn’t bad it’s average. Morrison’s is ok but I rate it near the bottom. No is really good but really expensive and not many if them around, like wise with shell.

  • May 7, 2018 at 11:33 am

    Surely the choice of fuel can be governed by the length of ownership of the vehicle, as like VW’s unwise 20,000 service intervals and DPF’s, the problems can arise for the next owner. My view is that if you plan to keep the car, use a branded fuel. If you’re going to hand it back after a couple of years you will probably get away with supermarket fuels and save yourself some money.

  • May 10, 2018 at 8:35 am

    Hi guys I recently well 6 months ago bought a VW Passat TDI 170 bhp good car so at first I was using shell because the guy I bought it from said brother you only use good fuel brother so I said cool until I realised evetytime I drove past a asda I could see passats filling up
    So I Thot hmmm time to try asda was ok for about a week then one day I decided to show my mate my remap errrm i put my foot down at some lights and the car sort of choked and jolted back as if the injectors had clogged up it did this nearly evetytime I put my foot down until I ran the tank empty..after I dediced to go shell fuel save n chucked in forte diesel cleaner ran it on motorway on low gears for about 20 miles each way after that it was absolutely perfect I have no dpf on mine as I got it removed on remap but IL tell you now if you have a pd engine don’t use cheap stuff I’ve noticed shell lasts a bit longer

    • May 20, 2018 at 11:29 pm

      You know that you are going to fail the new MOT which came in today as you have removed the DPF

    • May 23, 2018 at 4:03 pm

      Is it illegal to remove a diesel particulate filter?
      Yes, it is illegal. Owners face fines if caught (up to £1,000 for cars and £2,500 for vans) and removing a DPF can also invalidate your car insurance policy.

    • June 5, 2018 at 6:48 am

      As I understand it – the MOT test now involves a check to ensure that cars fitted with DPF’s at the point of manufacture still have them – they check for this and if the DPF has been removed it results in an automatic fail. IMHO it’s also an irresponsible, selfish and short-sighted decision to remove the DPF – engine designers know far more about engines than your average driver and it’s there for a good reason – sadly the internet is awash with stories about expensive bills and problems but there is no information AFAIK that puts the problems in context, i.e. against the figures that show how many diesel owners experience no problems – probably because they look after their engines and do as the manufacturer recommends e.g. does not ignore driving guidelines and responses to engine management instructions relating to DPF error codes and what to do regarding the regeneration process. So many people are happy to be manipulated by skewed, incomplete, unscientific data – if it doesn’t exist or is hard to find that’s no reason to “go with the info that is available (on the internet by unknown authors or unknown credibility)”

  • May 29, 2018 at 5:42 pm

    Your article misleadingly says “Petrol like this” (that is 95 Unleaded petrol) “is known as ‘super unleaded’. Confusingly, the petrol that is labelled as ‘premium unleaded’ on forecourt pumps (e.g. Shell Fuelsave) is actually standard petrol. When it comes to fuel, super is better than premium!”

    Your example is exceeding badly chosen because Shell is the only forecourt petrol supplier in the UK to offer two different grades of 95 Premium Unleaded petrol on its forecourts. Originally on launch in the UK in July 2010 Shell’s stated plan was to replace “Regular Unleaded” (also known as Premium Unleaded) 95 fuel at all of its UK filling stations with “Fuelsave Unleaded”. See for more information on the 2010 launch in the UK of Fuelsave. However because of perpetually unresolved issues with the enormous Coryton refinery in Essex being capable of supporting the latest fuel additives to this day Shell continues to confuse its customers by some of its forecourt sites (mainly in London and the South East of England within 45 miles of London) offering only Regular Unleaded and Regular Diesel but the rest of its UK fuel sites offering customers only Fuelsave Unleaded and Fuelsave Diesel. Also recently in 2017/2017 since the introduction of new stronger formula Shell VPower with more additives Shell has actually substantially cut the availability of Shell Fuelsave in the South East of England so that forecourt sites that used to carry Fuelsave Unleaded and Fuelsave Diesel like Shell Burnham have now reverted to Regular Unleaded and Regular Diesel. Outside London and the South East Shell Fuelsave Unleaded and Diesel seem to be universally available across the other regions of the United Kingdom

    When challenged on this situation Shell customer service in the Philippinnes have repeatedly lied to customers and told them that soon all Shell filling stations would have Fuelsave Unleaded and Fuelsave Diesel. But this hasn’t happened and this situation of two grades of 95 Unleaded fuel from Shell has been going on for several years.

    I have long term experience of using both these 95 unleaded fuels and can say that Shell Fuelsave Unleaded gives at least 5% more MPG than ordinary Shell Unleaded in my MR2 Roadster and that its MPG is in fact nearly as good as Tesco Momentum 99 Unleaded available from Tesco filling stations. Also I find that Shell Fuelsave Unleaded yields more or less the same MPG as Shell VPower, whereas Shell Regular Unleaded gets 5% to 7% less MPG.

    So it seems to me that your site clearly doesn’t know what it is talking about if it quotes Shel Fuelsave as an example of an ordinary fuel that the company marketing it wrongly gives the impression is premium in some way. Because Shell Fuelsave is in fact a superior version of its 95 Unleaded fuel with a better additives package than its Regular Unleaded 95 fuel that none of its competitors (all of whom only have one type of 95 Unleaded fuel on their forecourts) have so far developed.

    Perhaps you would therefore care to rewrite your poorly informed and badly written article?

    • May 29, 2018 at 6:53 pm

      Hi Julian,

      Thank you for your comment. My reference to “petrol like this” refers to the super unleaded (e.g. BP Ultimate, Shell VPower) mentioned in the previous sentence. I’ve edited the formatting of the article slightly to make this more clear.

      I didn’t realise that Shell was still selling regular unleaded (not Fuelsave) in the UK, thanks for pointing this out. It’s interesting to hear that you get noticeably better mileage from Fuelsave than regular unleaded.



  • June 7, 2018 at 2:53 pm

    After my son bought me an 05 Vauxhall Astra we spent hundreds of pounds trying to stop the emmisions light coming on after 12 months of trying my Garage noticed the Supermarket receipt in my car and advised me to stop using it and use a branded garage fuel problem solved immediately

  • July 4, 2018 at 9:59 pm

    I have a 4 year old Range Rover Evoque SD4 2.2 diesel engine done 33000 miles. It’s been serviced by Landrover since new. On a recent motorway journey the engine went into limp mode. The engines EGR valve had failed, it cost over £1100 to repair. I asked why this should happen at such a low mileage and how can I prevent it happening again.

    I get mixed answers but many experienced mechanics blame supermarket Diesel. Landrover disagree. Should I continue filling up with supermarket fuel or should I only use fuel from branded sources such as Shell, Esso etc

  • July 10, 2018 at 9:39 am

    I ran a BMW 520d 2011 vintage for 6.5 years on a mix of supermarket (mostly) and Shell regular diesel. I traded it in after 68,000 miles, after following the manufacturers service schedule, and had no problems. I put a bottle of diesel cleaner through it at about 50,000 miles just in case it was getting gummed up, but basically it ran well all the time. This model had a DPF but no AdBlue, and I did 70% motorway trips – which I am sure helped keep the engine clean.

  • July 13, 2018 at 11:05 am

    Have read these comments with interest, and have to agree with Bobby. My trusty old 2005 Volvo S60 2.4 litre 5 cylinder diesel starts first time and goes like the proverbial off a shovel. She’s never coughed once. Fitted a new battery about three years ago, but otherwise she’s all original. I’ve always used supermarket fuel, BUT have never stretched the prescribed service intervals, or missed a service.


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