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.

182 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.

    • October 2, 2018 at 6:02 pm

      My friend got a engine problem on Peugeot 2017y.First what they ask him where he fill the diesel…always filled on esso…They told him don’t take newer from those petrol station!

  • 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.

    • February 24, 2019 at 3:48 pm

      Sainsburys petrol is supplied by BP !I

  • 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)”

      • September 1, 2018 at 5:29 am

        DPF’s and horror story’s. Manufacturers know best? I have a Golf GT TDI (before was a Mercedes Vito CD108 Diesel). All these cars from new and all had reliability and operational issues. The Merc since new had issues under Warrentie (and out). Mercedes could not fix it properly, or would not. Every month it was in for repair and work was always on the injectors. Mercedes would only replace 1 at a time (not by set). Injector 1 – fail, then injector -3 fail. Next was injector -4, the 1 again and so on. Wiring issues and so on. At 40000Km, I was so sick of it, i repaired it myself. Importing 2nd hand injectors from Germany, disassembling them myself servicing/cleaning them. The car became much more reliable, although it had some issues. Mecedes, never again. I traded the Mercedes at great loss on a VW Diesel much better. This was not common rail like Mercedes, but the last of the Pumpe Duse and fitted with a DPF. The VW had small issues but a 200000Km, I still have it. Much more reliable and efficient. At the start and before 20000Km there were issues.DPF was the main culprit. VW said the was a Consumable item and needed replacement @ $7,000.- in parts (Consumable item bullshit). I removed DPF and EGR. Upgraded exhaust and now smoke issues all fixed. Next was a Tune. Performance Tune and EGR delete. So no error codes on Dash. No smoke, no running issues. A hell of a lot more power and at least a 20% improved Fuel Economy. More power and using less fuel with less reliability issues. All improvements, but if I am burning significantly less fuel. I am also running more efficient. Which means less pollution for the environment in producing and delivering less fuel Burning less fuel and also now no smoke, also means less pollution.
        In a nutshell, If done rite. Individuals can improve what the Factory gets forced to implement. Often Factory’s do not want the Technology in cars but they must, to comply. It;s the Laws that have it wrong, In fact all Pollution is measured as a percentage or PPM (parts per Million). And if you cannot reduce actual Pollution another-way to do is, increase the air in the tailpipe. How? A less efficient motor (air pump), pumping out more air simpl;y by being a larger capacity motor but pumping the same pollution/sometimes more pollution with much more Air. Now they comply with emissions, while actual Pollution is more (as in amount of pollution by Mass or Weight). then add to that cost to manufacture these parts, extra weight to vehicle. More developments costs and more fuel burnt. All bad issues and misleading to the actual problem.

    • January 15, 2019 at 9:27 am

      I bought a VW Nora 1.9 TDI with a of engine. When I bought it it had 6000 miles on the clock. When I sold it it had 247000 miles on it. All the time I owned it it ran on whatever the cheapest supermarket diesel O could find in my area was. When I sold it it still ran perfectly, the only reason I sold it was because the Dutch and flywheel were one and I was not going to spend £1000+ on a car with this mileage. The supermarket diesel did me proud

  • 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.

  • July 20, 2018 at 9:48 pm

    ‘…. you get what you pay for” … now I’ve been a a qualified commercial and retail technician since 1982. I’ve seen the technology change even to the where we’re now required to adblue as part of our refuelling.

    Petrol…. Quite simple. The higher the RON rating for fuel the better the burn?

    Diesel…. Ultra low sulphur and variants… do they work?

    Now let’s get technical. An engine is only as good as the driver and the maintenance schedule.

    ECR valves can clog due to;
    Poor quality fuel
    Using Bio fuel (not all engines can perform 100% efficiently.
    Poor maintenance
    Poor quality/incorrect viscosity oil
    Short journey/long idle times.

    Particulate filters can do the same (If fitted) and even with weekly use of Redex fuel treatment.. it doesn’t stop issues developing which can run into the thousands to repair.

    So how do get the best performance out if your car? Take your foot off the pedal for a start. If you need to get somewhere, leave in plenty of time.

    Use 1 premium fuel supplier for every 3 supermarket tanks.. Use additives like Redex Particulate Filter Cleaner (currently on offer at half price in Tesco) and put in a full bottle on the last of supermarket fuel with say 30 miles remaining. Now take your car for a run on a motorway.. 3rd gear at about 3… 4000 revs in 4th (the higher end revs, the better – use your common sense) to get the exhaust to a high temp and let the cleaner do its thing by acting with the spot and the high temp burning it off and flushing out deposits through the exhaust.

    Time the mileage to enable you to land at a premium filling station and fill with premium (most expensive) and then add another bottle to the tank just before you fill it. This will help regenerate the particulate filter. For a garage to do this, expect a bill if £197+VAT or have something like a terra clean (approx £300) by a specialist.

    Same principle for petrol?

    Yes, use a good quality injector cleaner, again I personally use and recommend Redex.

    Follow the simplicity of this will not only give you better performance but reduce potential issues with sensors giving false reader codes….

    By the way. The guy with the Range Rover… you need to challenge your dealer on your issue as that should be covered under Warranty regardless of fuel (except bio-diesel) as it’s not considered to be a wear and tear part and especially at that mileage you stated.

    Better economy?

    Lift your foot off the pedal! Find your engines sweet spot. Mine is 62 on the D4D 2.0L diesel and that’s constantly laden… since ive had it, ive increased from 350 to nearly 600 miles per tank and thats using air con and cruise control.

    If you do short journeys then you need to look at changing your filter and oil change frequency, especially on a diesel… every 6000 miles and buy a decent quality oil… cheap oil is a false economy. The only time you should use a cheap oil is part of an engine flush – another additive cleaner.

    One final tip.. when you start any engine… give it at least 90 seconds before you drive and when you have finally stopped. This will allow your engine’s oil pressure to stabilise, especially if you use a turbo engine.

    Happy motoring

    • November 19, 2018 at 9:49 am

      I have a 2010 Toyota Verso Valvematic approx 50000 on clock drives like a dream idles well and accelerates well.
      BUT following wrong oil not 0w20 used year ago on service and continued use of supermarket fuels the car occasionally went into Limp Mode after weeks of round town driving and warning lights saying check VSC system.
      When driving with VSC system off warning does not reappear.
      Have had new service using 0W20 oil and changed to Shell 99Ron and immediately MPG has improved.Not sure whether to try redex and would this cure a sooty EGR valve.all forums I have read say if car idles and accelerates and runs well some warning lights are erroneous but Limp mode can be scary and dangerous were it to happen at high speeds..

    • January 20, 2019 at 3:05 am

      There’s more to oil than viscosity index. Something tells me that your C&G isn’t in tribology or fluid dynamics

    • January 20, 2019 at 6:31 am

      That is an excellent piece of advice. I’ve always found my car to perform better with a fuel cleaner and of course a good yearly service.
      I’ve always maintained many cars have a speed which is ideal for MPG, mine is 65mph which currently gives me around 530-550 miles on a tank of fuel at between 45-47mpg and with mine being petrol I need to get the most out of it.

  • August 30, 2018 at 11:34 pm

    Always shell v power diesel never had a problem with it you get what you ay for. Keep your supermarket fuels i will stick with shell.

  • September 8, 2018 at 6:24 am

    I have a VW Passat 1.6 FSI BLF engine, currently 60k miles. Bought used at 58k. Both cats replaced as they were worn so I ended up replacing the entire system. The car was bought new in Scotland and the owner done 1000 miles maximum from new (2005) yearly based on m.o.t history. It has had VW servicing and parts only. As long life services of 2 years were used I started as soon as I bought it this year with what will be a yearly service. I always change air filter, fuel filter, spark plugs, antifreeze, gearbox oil and pollen filter when buying a used car (cam belt setup also). My Passat ran fine with regular unleaded but after a tankfull of Shell V Power there was a diffirence in power but I put this down to the higher octane. At the end of the day, a good service every 10k miles / 1 year with quality and correct grade of oil and no short driving trips should keep any engine healthy. For those who suggest addatives like Redex etc, for around £7 for that bottle of addative (or much higher) you could use top end fuels with better results and no threat of potential catalytic converter damage. You’ll save far more money useing V Power or other top fuels than buying expensive additives, just do the maths on a tankfull. I’ve treated all my petrol and one diesel (VW Sharan) cars the same. All kept for 5 years and not one had ever broke down. I do travel monthly for a few days away including the Scottish Highlands (yearly), Tomintoul near the Cairngourms. Treat your car care and it will be reliable, dpf problems are common now but again that’s due to too much town driving. Its the Devil in the detail.

  • September 29, 2018 at 11:55 am

    Regular servicing by main Volvo dealer my V70 AWD with 135000 miles on clock o total supermarket fuels had no engine injector problems plus very little oil burnt. However my latest V40 D4 inscription appears to run better on Shell/Esso premium. Old adage ” you pays your money and make your choice.” Additives are computerised at the terminal so my family who is in the petrol and distribution business tells me their is a difference between supermarket and roadside stations depending on the additive balance. Red X is always available if in doubt!!!??

  • October 9, 2018 at 3:26 pm

    I found this forum by accident but so glad I did.
    I drive a 2008 Peugeot 308. The engine management light comes on and goes off when it feels like.
    I get the antipollution warning on the dash board.
    The car is serviced the only fault I have made is using Tesco diesel.
    I have started filling up now with shell’s top quality fuel hoping this will solve the problem.
    If anybody has any other suggestions they would be most welcome.

  • October 14, 2018 at 3:54 pm

    Anyone driving a diesel and doing less than 10,000 miles a year – unless they are all motorway miles – is driving the wrong engine type. Modern diesels need to clean the Diesel Particulate Filter – and that needs it to be hot and run hot for several miles to work.

    Anyoen doing short journeys in a diesel – less than 10 miles – is asking for problems.
    Anyone driving and never using higher revs,,, 3,000 plus – regularly – is encouraging carbon build up in the engine.

    We drive a 15 year old Toyota diesel on short runs only : use only diesel with lots of cleaning additives and run it at 3,000 rpm + for 20 miles the day before an MOT in order to pass the MOT smoke test..

  • November 22, 2018 at 5:35 pm

    a lot of bollocks to read :/

    the DPF filter at the prices they do its a ripoff, why? because they can! easy money man ez pesy money all because they enforced the emission legislation, do u really think anybody cares for world pollution from those companies? u have to be dumb and extremely naive to think so, all the DPF do is clog up and then u cash in and make ppl happy

    probably nobody of u had any chemistry lesion in school, the carbon build up in dpf is a fucking rock solid i mean ROCK, did u have seen a rock flying and polluting the air? man do u? man… like literally? does DPF reduces the gases that passing trough it? hmm not really… because this is what catalytic converter does it…

  • December 9, 2018 at 2:25 pm

    Why does,uk not avoid speculation and simply conduct a tests – standard car, standard drive, mpg. How hard can that be?

    • December 11, 2018 at 7:38 am

      Hi William,

      It would be interesting to test consumption of different fuels, but it would be far too big and expensive for us to manage. We’d need multiple cars and multiple fuels. We’d also need some way to switch between fuels without them being mixed in a car’s fuel tank. And some way to measure mpg with scientific accuracy.

      Unfortunately, it’s much too big a project for us to be able to do.



  • December 15, 2018 at 11:11 pm

    Shell v power, and Esso supreme are the best petrols in my opinion. They make the car smoother, and quieter and seems to make the engine more responsive and higher MPG, however you have to drive leisurely to get good MPG, as with the increased power response can hammer the MPG reading, if that makes sense.

  • December 17, 2018 at 8:04 pm

    Hi All,

    I`ve got a mini cooper 2002 1.6 petrol. I was using Shell FuelSave, full tank (40L) -230 miles. I moved in a small town with just 2 petrol stations. I`ve used BP petrol and i drove the same, 230 miles, then i start using Jet`s petrol… surprise…. I am driving now around 280-290 miles per tank. How it is possible?


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