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Livi
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I've always been happy to use supermarket diesel in my cars up till now, but my son has talked me into trying out premium diesel in my my new car on the recommendation of some of his friends/colleagues.

 

I have to admit that the car seems to run much more smoothly and shows a slight improvement in fuel consumption ( but not enough to justify the extra costs).

 

My query is more about what goes into the premium fuels.

 

The filler cap on my car has "no additives" stamped on it.

 

I'm no chemist and have no idea what extra ingredients,if any, are in the premium brands.

 

Am I in fact introducing "additives" by using premium fuel and could it be harmful to my engine?

 

Apologies if this has been covered before.

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Here is a reply by a chemist who was known to many of us Rob-Jax

 

This topic reappears every so often, but in essence I'll quote my answer about diesel fuel - and petrol is pretty much the same story:

As the UK Representative to CEN WG9 (European standards committee for all motor vehicle fuels) all pump fuel in Europe is produced to meet the relevant EN standard - which you will see written on the pump body.
The major difference between the supermarket fuels and the branded fuels is the exact nature of the additive pack added to the fuel when it leaves the refinery - common rail pump lubricants, injector cleaners, etc.
Synthesised Diesel
The exception to this is the new "synthesised" diesel fuels, such as BP Ultimate (actually researched by Aral in Germany), Shell V-Power (may be called something else in the UK), and Total Excellium. These fuels are manufactured in the refinery by joining simple petroleum hydrocarbons into an exact diesel fuel - you'll need some experience of university level Chemistry to follow what they do - so just accept that they are better - higher cetane rating, better additive pack, etc.
Normal Diesel
This is a straight distillation fraction from crude oil, produced by the nearest refinery to the fuel depot - so for instance, diesel refined by Shell may be sold by any of the other retailers close to that Shell refinery. The major difference is the additive pack - which is brand specific - and any specification difference imposed on the refinery by the other retailers - and the addition of bio-diesel.
Bio-diesel
Another one of our EN committees, pump bio-diesel is a blend of normal refinery diesel (95%) and (5%) of pure bio-diesel. This is an EN standard and all EU countries will be (or are) selling this bio-diesel as a direct replacement for normal diesel. All the car manufacturers have accepted this 95:5 blended fuel, and we are working on specifications for a 90:10 blend.
Pure bio-diesel is manufactured by mixing and heating vegetable oil with methanol (methyl alcohol) and sodium hydroxide (caustic soda). This splits the vegetable oil into glycerine and fatty acids, which immediately reacts with the methanol to form a "fatty acid methyl ester" or FAME (bio-diesel).
FAME is perfectly fine as a diesel fuel, it has very good lubricating effects - and replaces the lubricant additive in a normal diesel fuel - except that it is not as stable as normal diesel - it tends to go "sour" or "rancid", which is why the car manufacturers don't like you to run a car on pure bio-diesel. Not a problem as a 95:5 blend.
Vegetable Oil
Reasonably OK for an old (pre 1995) diesel engined car - except that the car won't start on cold vegetable oil, but once the engine is running it's OK.
Other problems are that vegetable oil quickly turns in a gummy glop (like the linseed oil that artists use) and the car's fuel system and that the engine needs a lot more maintenance - blocked injectors, gummy residue in pumps and cylinders, etc.
After market additives
After market products like Millers improve the cetane rating of standard diesel, but only when the engine is cold - interestingly it doesn't help a hot engine - so cold starting is usually quieter but no difference to a hot engine - and Millers does provide good, additional pump lubricity.

Self Tuning Engine Computer
So, if your diesel engined car "self tunes" then try Shell V-Power, BP Ultimate, Total Excellium - I see between 3% and 5% improvement in fuel consumption. My Mercedes C270 returned 52. 8 mpg driving from Rotterdam to Wendover yesterday - on Dutch Shell V-Power - 320 miles at speeds of around 60, 70 and 80 mph depending on the country / road speed limit - using the electronic speed limiter. If not, stick with the regular diesel fuel, and add Redex or Millers at the recommended dosage level - adding more won't improve the performance. And don't be dismissive of supermarket fuel, it can and often is identical to branded fuel.
And if you add Redex or Millers or switch to a branded fuel, then any change to the cleanliness of the injectors won't show itself for quite a few hundred miles, but pump lubrication and maybe a higher cetane rating will show an effect much sooner - depends how much old fuel was in the tank and fuel lines - and how much the old fuel dilutes the action of the new fuel.
So is there a difference between supermarket and branded fuel ? - there can be - but often there isn't.
How can you tell if one fuel is better than another?
To compare the fuel consumption, you need to exactly reproduce two journeys - exactly the same speed, exactly the same acceleration and braking, and under identical conditions:
Atmospheric Pressure
A one percent change in air pressure has an identical effect on power and torque - so driving on days with high pressure makes the engine generate more power
Temperature
Driving on hotter days reduces engine power.
Humidity and Rain
Driving on days when it is humid or raining significantly improves engine power - water injection is used in truck racing and sucking in damp air has a similar effect in increasing power.
These produce percentage level effects on mpg - making it difficult for the driver to make comparisons. Driving on a cold, damp day may see an improvement of 3% or more compared to a hot, dry day.
Even more important are the effects of different traffic levels and the inability of drivers to EXACTLY reproduce a journey on UK roads, for instance:
Speed
A 1 mph increase in speed (say 60 instead of 59) will make about a 2% difference in fuel consumption - rolling friction and wind resistance increase exponentially - on top of the extra fuel need to spin the engine that bit faster.
Unless you drive everywhere using an electronic speed limiter or digital cruise control then it's impossible for most drivers to reproduce even a constant speed.
Acceleration and Braking
Big percentage differences here - and unless you are driving on an empty test track - the effects of other traffic, let alone how you drive the car, have effects at least as large as the difference attributed to different fuels.
Summary
There is a reproducible improvement of between 3% and 5% by buying the synthesised diesel fuels - BP Ultimate, Shell V-Power, Total Excellium, etc - compared to the standard branded diesel fuels.
There are smaller differences between supermarket and standard branded fuels - sometimes they are physically the same fuel - sometimes they differ only by the additive (cleaner) pack - and sometimes they are different.
Day to day variations in the weather, driver reproducibility and traffic make it very difficult for drivers to reproduce journeys.
Comparing two fuels
If you do want to make a comparison, drive your car until the fuel tank is almost empty, then fill the tank and after you have driven 200 miles (any old fuel should have been used up), drive at a fixed speed on a motorway for 10 miles and record the fuel consumption.
Then the next time you fill up, repeat the exercise with a different brand of fuel - but remember to test on exactly the same section of motorway and on a similar day.
Checking your fuel consumption over normal driving, in stop start traffic, over a period of weeks - just tells you that you have had to driven differently.
And don't forget the placebo effect. Robert

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On many tests and including rolling road I haven't found any difference between the likes of V-Power or Morrisons finest. What does make quite a marked difference is the addition of a small amount of 2 stroke oil to a tank of diesel. It does make engines smoother and quieter for sure. There is a lot of evidence supporting this and the reasons why it works on the net.

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On many tests and including rolling road I haven't found any difference between the likes of V-Power or Morrisons finest. What does make quite a marked difference is the addition of a small amount of 2 stroke oil to a tank of diesel. It does make engines smoother and quieter for sure. There is a lot of evidence supporting this and the reasons why it works on the net.

I have heard of this, but have never tried it. We avoid supermarket fuels as one thing we did notice with the diesel is that there was more smoke coming from it on start up. With the petrol vehicle, it did does seem smoother. I don't think there is any mpg to be gained although we use BP as much as possible. IMHO the only difference is a cleaner engine.

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Among the list of things i'm really fussy about, is fuel and which one to use. We ran our original work 2006 Vivaro for nearly 300,000 miles. Other than the first 30,000 miles where we didn't own it, we only ever used premium diesel, either V-power, or BP ultimate. Now, this isn't to make it go faster, but I personally opted for this fuel because from my limited knowledge of fuels and diesel engines, we hoped it would keep it far cleaner inside the engine, injectors, fuel pump etc. Did it? Who knows. . all I know is that van never had any issues with the engine, or it's fuel system unlike many older Vivaro's that may or may not of used good quality fuel. (it's still running perfectly now)

Our new 2015 Vivaro which we have had since zero miles, has had only premium fuel used from day one for the same reason, and again, the engine has been faultless for the 85000 miles we have done to date. Ok. everything else around the new Vivaro has either fallen off, or broken! but the actual engine and fuel system has been faultless. The same goes for my Motorhome, and my wives Mini. We are in the process of changing the Vivaro for a new VW T6, and this will have the same treatment.

Yeah, there will be those that say it's a waste of money, and the extra i've spent over the years might of out weighed the cost of any potential fixes if anything had of gone wrong with the fuel system, but for me as a business that has a diary that has no time for breakdowns, or lengthy dealer trips sorting out issues, I will continue running my vehicles the same way.

 

By the way, if any manufactures read this and want to examine the internals of an 85000 mile Vivaro that's run on 100% V-power (with receipts to prove) from zero miles, I have a nice looking van that could be yours for a snip of the value of the potential evidence of what the fuel benefits actually are to an engine in the real world. . . . ;)

Edited by Tourershine
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I drove my Peugeot 306D Turbo for 106000 miles from new on supermarket diesel and never had any engine problems and it is still going strong. ,I see it quite often.

knarf

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I drove my Peugeot 306D Turbo for 106000 miles from new on supermarket diesel and never had any engine problems and it is still going strong. ,I see it quite often.

knarf

My 2010 Volvo V70 d5 did around the same mileage on the cheapest fuel that was going. No issues at all

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Unless anyone has tried both fuels over a long period of time then it is impossible to make a realistic comparison.

If they have always used premium and the vehicle has done 300000 trouble free miles how do they know it would have been worse using supermarket fuel?

knarf

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I only use posh diesel (if possible) and it works out about the same cost wise as normal diesel, it burns cleaner so should keep everything tickety-boo :)

Paul B

. .......Mondeo Estate & Elddis Avanté 505 (Tobago)

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My VW Passat TDI (2005 1. 9 130bhp) achieved 306,000 miles as a taxi before I retired. I saw it a year later, still in use as a taxi (so probably another 50,000) My filling station of choice was Sainsbury's (usually the cheapest in the area). Never seriously considered premium fuels, but it did get treated to some Redex occasionally.

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My cars usually run on Morrison's soup, but when considering towing the van I use BP Ultimate. This super fuel seems to give my little car a bit more power, especially on the hills. There is a trend of thought who suggest the use of certain additives will achieve the same results. This is probably correct as it increases the cetane value of the fuel but I have not bothered to do the economics of it so far.

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I've pondered this issue as I always use supermarket fuel. I asked the service manager at my dealer about this. I should say that the dealer only sells one make, and has been a Mitsubishi dealer for a long time. The service manager has been there for as long as I can remember too, and his advice was carry on using supermarket fuel, they had never seen a problem with it. As for the premium fuel, tried it and it never made any difference.

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My current CR-V, does not like any supermarket fuel at all, the engine is a lot more noisy, and is lumpy on tickover. If I use Texaco, Esso, Shell or BP it's much better, and this is on normal diesel, not the "super" stuff. Contrast that with my previous Vectra diesel, and that would run on practically anything, which it did for the seven years that I owned it and it never missed a beat.

My CR-V however, seems a lot more sensitive.

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On the marmite question of whether or not a dose of two stroke oil etc to each tank of diesel, one has to assume that if any real benefit arose from the additive, it would have been leapt upon by diesel refiners with such pretreated fuel being sold at a premium as diesel plus plus super fuel or whatever.

 

Of my diesel cars, a Corsa 1. 7 DTi only ever got supermarket fuel from new to ten years /150,000 miles, a Seat Leon 1. 9 TDI and two Freelanders (one a TD and the current one an SD), less miles covered but all fed supermarket diesel, none ever cost a penny beyond consumables, (oil & filters) engine wise.

 

I will stick to Messrs. Morrison, Sainsbury and Tesco, heavy oil suppliers to the disbelievers of marketing ploys and additional additives.

Edited by happynomad
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Nice to see the late RobJax quoted again. ...full analysis special!!

 

Trade mate who runs high performance vehicles uses the usual Greenergy supplied diesel at his local Tesco but every 4th fill goes Premium. ....me supermarket all the time. ..my Rexton loved it.

 

Geoff

Kia Sorento KX-1 CRDI 4WD towing an Elddis Affinity 530

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I've found I get around 2 to 3mpg more on premium, but it costs a lot more, around 20p more a litre, so a waste of money.

 

No noticeable difference in performance, Cx 5 towns like a train on any diesel.

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I used to add a bit of premium 2 stroke oil to an old sorento (no dpf) and it did take a bit of the usual diesel knock away and made it a smoother. As for increased mpg I have no clue. At best I got 35mpg from it and mid 20's towing

 

I now have a custom van and run it normal super market diesel. Not once in 45k miles has it missed a beat or even threatened to. No misses coughs or hard to starts. Just on the button every time.

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I have honestly never been able to tell any difference between any fuel (of the correct type!) in any of the petrol or diesel cars in our household over the years.

 

I just fill up where convenient or where has been local to where we've lived and worked over the years.

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Unless anyone has tried both fuels over a long period of time then it is impossible to make a realistic comparison.

If they have always used premium and the vehicle has done 300000 trouble free miles how do they know it would have been worse using supermarket fuel?

knarf

 

A very good point and I have done exactly that.

 

I covered 20,000 miles using BP Ultimate and compared it with 20,000 miles using Supermarket fuel. The absolute mpg was improved when using Ultimate but it wasn't enough to be cost effective. I did not go to the extreme of an engine strip down to look for any evidence of differences within the engine.

 

I was an oil company employee for nearly 25 years, where for half of that time I ran a company car, other than for the 20k miles referred to above my employers mileage allowance was always used to buy supermarket fuel. Many of the miles I travelled in my company car were to visit fuel distribution terminals up and down the country, such was the nature on my job.

 

I would urge folks to refer to post number 2 and read, in full, the quote of our dear departed contributor Rob-Jax, it is an excellent summary of UK road fuel technology.

Edited by jetA1
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My old Land Rover D2 discovery always struggled to pass the smoke test at MOT time. I put a tank of premium fuel in before the test and it sailed through so there must be something in the fuel to make a difference. I use premium fuel on my new DiscoveryD4 but my day to day drive a Vauxhall Astra supermarket fuel is fine although I put a tankfull of the good stuff every third fill up

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I always use premium fuel in todays vehicles . .. better mpg . . better performance equals more efficiency which equals less pollution . . Simples.

 

Just a note to all those engine software remap fanatics, most of the more reputable companies (That's not an endorsement) recommend using a premium fuel after a re-map. . Food for thought :blink:

 

Don't think you can gain any results by putting in one tank of premium to sample, you'll need three to four refills and if your vehicles engine hasn't been well maintained and of higher mileage don't bother, because you'll probably haven't got the best piston in the pot.

 

All my own opinion from experience and being within the motor industry for a very long time :( . . Please don't ask me to explain, because I've done enough of that in past CT posts on this topic and it always turns into a Harry Hill :o

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Absolutely. On the petrol front, really high performance cars need the special fuel. But your average Kia Sorento or Nissan XTrail. Nah. Stick the cheapest in. ..

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It's a bit like the argument over organic food.

My sister swears that free range eggs taste different to supermarket eggs,I bought some eggs from Tesco and put them in a local farmers' free range box and served them up for breakfast.

I asked her if she thought the eggs were worth the extra money I paid to get free range ones and she said they were lovely.

knarf

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