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Can't say i've noticed a huge difference between premium brand fuel and the supermarket stuff.
I do mix and match depending on where i am at the time (travel for work).
Price wise the local ASDA is cheaper by an average of 3p a litre on diesel (over branded fuel). The nearest Esso is the most expensive at 8p a litre more.
As to Millers, how does it compare with RedEX (is it even the same sort of deal?)
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Use shell
Much higher cetane rating which means the fuel ignites easier. When a fuel is essentially more flamible it burns more completely. As oppossed to a supermarket fuel which has no/low amounts of cetane booster (2-EthylHexylNitrate) which has a lower cetane rating, UK spec 51.
When our diesel cars re-circulate exhaust gasses, NOX, this burns cooler in the combustion chamber and the fuel burn's incompletely, forming carbon, soot.
A higher cetane fuel like Shell fuelsave or bp ultimate has a centane of around 56/57. More fuel is therefore ignited at any air/nox mix and leaves less soot.
I'm sure you are aware, carbon in the internals will eventually lead to component failure, the first stop, DPF.
Edited by OldSkoOL on 18/01/2011 at 23:52
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Perhaps OldSkoOl, we'd have more confidence in your posts if they weren't double spaced and contain so many typos? (centane?)
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Dyslexic Tom
As for spacing, this editor double lines on return.
Edited by OldSkoOL on 21/01/2011 at 09:42
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I avoid supermarket fuel, because once they have closed the independants, they jack up the prices. The fuel itself is sometimes better, sometimes the same sometimes worse. Unless you have local inside knowledge of fuel distribution, then one will have to play it by ear.
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Perhaps OldSkoOl, we'd have more confidence in your posts if they weren't double spaced and contain so many typos?
Haway Tom its the content of the post that really matters.
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It's all the same stuff guys. It all comes from the same refineries. They all chuck their branded additives in, but they make no difference and it's only to give the advertising boys something to talk about in the adverts. Seriously, if they didn't then what would they put in the adverts? "Fill up at Shell. We have diesel and petrol. And pasties."
Not that BP or Shell would want you believing that.
As someone near the top of the thread says, do the maths. You might think you notice a difference, but that is inbuilt human bias and the numbers will show no difference.
The only way you'll ever notice a difference is if one filling station goes onto (or comes off) winter diesel sooner than another, then you'll be getting slightly different stuff at different places. My numbers show slightly lower mpg in winter, but whether that's a difference in winter diesel or just the effect of lower ambient temperature, I don't know.
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"They all chuck their branded additives in, but they make no difference."
Additives can raise the cetane rating of diesel, which allows the fuel to burn more efficiently.
I'm not an expert, but a little research indicates that Shell FuelSave diesel has a cetane rating of 55-58 and is typically 56-57, whereas the standard cetane rating for diesel is 51. I don't know where supermarket diesel stands on cetane rating - the standard minimum, possibly?
Apparently raising the cetane rating above 55 is pointless, as the engine can't benefit from it. I am also aware that, in discussing fuel quality, cetane rating is not the only important factor.
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Ahh - sense at last. (from gfewster).
Diesel engines are fuel insensitive (what a brilliant invention) and will give an output which is a function of the fuel's calorific value unless detonation occurs. To avoid this, a minimum cetane value is required and automotive production engines are set to operate within this limit - defined by EN590.
As is rightly pointed out, a change to Winter fuel will generally degrade engine output (or increase consumption for the same duty) as it has a slightly lower calorific value than Summer fuel. Simple.
Magical "lubricity" additives will not make up for a poorly designed fuel system. If the thing is any good, it will run for an adequate lifetime on any fuel which meets the engine maker's spec. A marginally designed fuel system will always be just that.
659.
Edited by 659FBE on 24/01/2011 at 12:53
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659FBE, I thought diesel engines did detonate?
Perhaps I'm wrong (my knowledge of diesel systems is patchy to say the least) but I always thought that diesel engines ignited their fuel through precisely the same process of detonation (squeezing the vapour/air mix until it heats up and explodes) that petrol engines are trying to avoid?
Isn't that why they're louder and need big heavy flywheels to absorb the firing impulses? Isn't that why they have no spark plugs and much higher compression ratios?
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Ahh - sense at last.
(from gfewster).
Diesel engines are fuel insensitive (what a brilliant invention) and will give an output which is a function of the fuel's calorific value unless detonation occurs. To avoid this, a minimum cetane value is required and automotive production engines are set to operate within this limit - defined by EN590.
As is rightly pointed out, a change to Winter fuel will generally degrade engine output (or increase consumption for the same duty) as it has a slightly lower calorific value than Summer fuel. Simple.
Magical "lubricity" additives will not make up for a poorly designed fuel system. If the thing is any good, it will run for an adequate lifetime on any fuel which meets the engine maker's spec. A marginally designed fuel system will always be just that.
659.
So 659...in laymans terms it does not matter one iota which diesel fuel you put in...
this is important because Asda at the moment priece is 28.9 and shell is 33.9
I have been using Shell becuse of their publicity etc
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It's worth standing back and considering what we would want to achieve in an ideal world if all engine and fuel parameters could be chosen at will.
For a smoothly running diesel engine to give its optimum power output, we would need to define precisely the instant of ignition relative to crank angle and also define the rate of combustion - and consequently the rate of rise of gas pressure. Other fuel dependent factors will include droplet size defining smoke, waxing, lubricity, energy density, cost and many others.
Detonation perhaps requires some defining. In diesel terms, I would define detonation as uncontrolled combustion, both in terms of the crank angle at the instant of combustion and the rate of burning. So, if we are anywhere near our ideal of having a smoothly running engine producing its optimum power, we would need to know the delay time (ignition lag) between the start of injection and the commencement of combustion (exothermal output) and its rate of burning. If we don't, combustion becomes semi-random and the engine is, in diesel terms, detonating.
Without writing a text book, ignition lag is determined by, amongst other things, the fuel's cetane value. This value is important because fuel is common to all engines for a specific duty - other engine parameters determining ignition lag, such as nozzle design, are under control of the engine designer. In practice, a known cetane value in a diesel fuel will also fairly well define its rate of combustion - so it's a very useful yardstick.
There isn't a lot of advantage in operating with fuel above the required cetane rating though, whatever oil companies may like to tell you. If your chosen retailer can demonstrate that his fuel meets EN590 or whatever standard the engine builder requires - buy it - as long as it's clean and free of water.
659.
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"In practice, a known cetane value in a diesel fuel will also fairly well define its rate of combustion"
We're in sticky territory here. The rate of combustion is determined by thermodynamics-and kinetics. The cetane rating is a measure of a fuel's tendency to autoignite ie the thermodynamics. A higher cetane rating will have a shorter ignition delay, so the fraction of fuel burned in the pre mixed phase is smaller. But diesel combustion (especialy at high load) has two phases; the premixed phase and the diffusion controlled phase. The diffusion controlled combustion is governed by the rate at which fuel and air mix and has nothing to do with cetane at all.
I'm not convinced that a higher cetane rating is better either. High cetane fuels always promote sootier combustion, and this combustion will occur closer to the injector nozzle, where you really don't want soot deposits.
"So, if we are anywhere near our ideal of having a smoothly running engine producing its optimum power, we would need to know the delay time (ignition lag) between the start of injection and the commencement of combustion (exothermal output) and its rate of burning. If we don't, combustion becomes semi-random and the engine is, in diesel terms, detonating. "
You can't really have a smooth running engine making maximum power. Maximum power is achieved by maximising the difference between the compression work and the expansion work. This is achieved by an instantaneous pressure rise when the piston is at TDC. Unfortunately sudden pressure rises give rise to audible knock and noticeable harshness. In diesel combustion, knock occurs at the start of combustion, in spark ignition, knock occrs at the end of combustion. Slower combustion gives smoother torque delivery, but at the expense of efficiency. The driver must accept an inevitable compromise betwen refinement and economy.
"if we don't, combustion becomes semi-random"
Unlike spark ignition engines, diesels do not suffer cycle-by-cycle variation since combustion can be tightly controlled by the rate of injection. Of course if the conditions between different cylinders varies, then the combustion cannot be optimised for all cylinders (unless each injector was individually controllable).
Agreed. There are far more important factors in diesel fuel. The lubricity, oxidation resistence, vapour pressure, anti-waxing, and detergents are far more important than the cetane rating. But people like simple numbers. Just like the size of their wheels, bigger is not always better!
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The additives include detergents. There have been some tests that show benefits, over and above EN590, which does not currently give a standard for detergency. So I don't think it's all advertisers puff.
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There are lots of "tests" - I used to manage some of them.
If you have a vested interest it's dead easy to design a test which will show some advantage or other - think cosmetics.
If not, and you are more concerned about getting for example, the most work out of an engine for the money you burn, you will test carefully for the things that matter. Engine operators who burn millions of litres of fuel per annum are not fools.
Over the years, the results of this testing will be used to determine a standard - for everyone's benefit.
659.
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Engine operators who burn millions of litres of fuel per annum are not fools. Over the years, the results of this testing will be used to determine a standard - for everyone's benefit. 659.
So why do the high pressure fuel pumps and injectors on common rail engines fail? I was led to believe that it was down to fuel sensitivity - or the lack of lubricity in the fuel being used. And according to your previous posts, the Ford systems aren't one of the better ones. Why?
Time will tell whether the Bosch common rail system used currently will be reliable at higher mileages.
Edited by corax on 24/01/2011 at 19:43
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What do manufactures recommend for
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What do manufactures recommend for a high presuure
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Why do they fail?
Because the technology and manufacturing methods are relatively new and untested.
I believe that a major problem with modern cars is that 'new tech' (much of it mandated by legislation) is rushed into production cars without enough development time, field testing, or just being allowed to move on at a sensible pace.
Think diesel particulate filters, dual-mass flywheels, etc. To meet modern expectations 99.999% of these need to be good for 250k miles without failure. But they aren't, not by a long shot.
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Dead right.
Euro regulations are being introduced at too higher rate to allow for proper engine development between stages. This is a serious mistake which the politicians don't seem to appreciate. The inherent thermodynamic advantages of the diesel engine are being jeopardised by this shortened development cycle.
The huge practical advantage of the diesel - part load efficiency - is now denied to many users by the fitment of DPFs which will sometimes not burn off under operating conditions of light load.
So, we have the ridiculous situation of taxi drivers reverting to petrol engined vehicles and users of diesel cars fitted with 6 speed transmissions being told not to use top gear at 70 mph as the engine speed is too low.
Crazy - I'll stick to my Euro III.
659.
Edited by 659FBE on 26/01/2011 at 15:11
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I kind of agree about euro regulations being phased in too quickly, but I disagree about your petrol/diesel analysis. There's nothing inherently efficient about diesel engines-the primary advantage is that they run lean and unthrottled. But petrol engines with stratified charge injection can operate lean and unthrottled and enjoy low load efficiency comparable to diesel.
But for some reason, particulate and NOx emissions are acceptable for diesel fuelled engines, but not petrol ones. In Europe diesel engines have enjoyed significantly laxer emissions standards than petrols, and fuel that is relatively a lot cheaper. Don't forget a gallon of diesel is heavier than a gallon of petrol, and it contains ~10% more energy, and 10% more carbon. On an equal basis it should be 10% more expensive. Diesel fans are complaining because they are finally being subjected to the same standards as petrols. Now either the standards are necessary and all cars should meet them, or they are not necessary and no car should be obliged them. But technology specific regulations are unfair. Set a common standard and let all thetechnologies fight it out on an equal basid.
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I live in holland on top of the bigest gas bell in europe, Holland has a thing about LPI car installations and some years ago diesel`s. What came out of this adventure by shell was liquid gas mixed into Diesel. Thus Shell V diesel. If you know that your shell comes out of Rotterdam then it is that fuel plus it does not stink the same as the stuff. Coming your way soon will be very strict annual smoke test. My friend always tanked supermarket,every year failed the smoke test cost him 400 euro`s per year to get his system cleaned. I always used Shell V and never any problems.
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Just read a article regarding fuel and the Shell V and Bp Ultimate also Total Excellium are different products all together.Not just base fuels with a additive.I dont know if it makes a difference in the long run time will tell.I use the higher grade fuels for my TDCI for the reason opahale mentioned.
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Hi, if I may revisit this again with a question. I'm slightly confused or uncertain and the reason is - I've read many times before that due to the lower sulphur content (which apparently provide some/all of the lubrication in diesel) and the subsequent inadequate addition of lubrication additive by fuel companies the new common rail design suffers as it depends on the fuel for its lubrication (as per 659FBE words somewhere else) and not the engine oil like the old PD system. In the same spirit Honest John recommended to someone to use Shell V power diesel as it contains more or better additives for lubrication purposes. I have no scientific way of verifying whether either of the above statements is correct. In my ignorance I simply believe that both 659FBE and HJ have the proper proven knowledge when they say that the common rail system depends on the fuel for its lubrication and that Shell has better lubrication than the other brands. For me this all comes to a very clear conclusion. However, now I read that it does not matter which fuel you use – supermarket or Shell or or – the additives they add does not make any significant difference. Could anyone with the appropriate knowledge clear my confusion up please? For an untrained person like myself, is there any noteworthy benefit to my common rail fuel system in the long run to use the diesel from Shell (whether it be their fuelsave or V power) over any other (the cheapest supermarket etc)? Perhaps one last question, according to some there is also much benefit to be had (and allegedly studies to back) from adding two stroke oil 2SO to the diesel (200:1 ratio). Is that worth doing – according to HJ not. As mentioned above HJ recons don’t uses 2SO just use Shell V power? If anyone has time to answer some clarity would be much appreciated. Thanks
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When I owned a diesel with a DPF I always used Miller's Diesel Plus. The thinking behind that was it was an additive which made the fuel up to the standard of V plus etc but at a cost oer litre lower than the pump price difference. Theoretically all fuel meets the relevant BS specfication so all fuel should be OK for one's engine. Who knows? I should add that I did a major misfuel and after putting in at least 10 litres of petrol I topped of with diesel and a triple dose of Millers and the car is still running OK 70K miles later. The pump lubrication is what matters, the DPF is a secondary consideration and not much affected by fuel/grade quality SFAIK.
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Got 2 diesels with DPF and the only time we don't use supermarket fule is when we go on holiday, no supermarkets but the fuel is an unknown to me TorQ brand. We have never had a problem and I don't expect one since all the fuel sold in the EU is to BS EN590 minimum.
I would never use aditives since most manufacturers specifically say don't as they may affect the performance of the DPF.
The pump is lubricated well enough by the diesel itself, does not need anything else.
Engine oil type is critical to the health of the DPF, it must be a low SAPS type, both our cars require C3 spec. The handbooks clearly state that other oils will cause ash to build up in the DPF which a regen cannot clear.
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I read what you write but I am not clear how, if an engine is not burning any oil, it can be making ash in the DPF. Will the slightest amount of oil reaching DPF cause a regen problem?
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I read what you write but I am not clear how, if an engine is not burning any oil, it can be making ash in the DPF. Will the slightest amount of oil reaching DPF cause a regen problem?
It does seem to be generally true that cars fitted with DPFs require ACEA-C3 (Low ash) oil to be used. Presumably the engine developers work with oil chemist to determine exact requirements.
When DPFs were introduced on diesel Hyundai's, a number of dealers didn't spot this change and used cheaper C1 oil as they did before - it took a number of cases referred via Hyundai UK and several repeat technical reminders to get all dealers in line.
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Until the vendors are willing to catagorically state how 'special' fuels differ from ordinary fuels, I'm putting it down to the usual retail trick of price differentiation.
All this arcane nonsense about secret formulas is rubbish. It's not as if rival refiners don't have access to mass spectrometers, gas chromatography, x-ray diffractometers and all the other standard kit that will give a precise breakdown of every compound present in the fuel .
The only reason to be coy is because there really isn't much difference at all. Look at Shell's website. Animations of a Scottish brunette in an immaculate lab coat holding a conical flask of effervescent pink liquid. Looks Sciencey so it must be good. Throw in a picture of Ferrari to reinforce the performance feel. It's just suggestion, no factual information at all.
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The brunette is there to add lubricity ...
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Re "all the fuel sold in the EU is to BS EN590 minimum" You may think so. There is a black market on the fringes of the EU, especially in NI, and that may be so in other areas where there are tax discontinuities. In any state in the EU, need to beware of entrepreneurial/very cheap sources. With cut-backs in enforcement, the gate guardians are in retreat. Entropy as a political aim?
Edited by nortones2 on 17/11/2012 at 22:18
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I used to work for a large oil company who supplied fuel to all the major supermarkets, all the fuel is identical - however the supermarkets buy cheaper additive packages, all oil companies also buy fuel off each other when they have refining capacity issues or when the price is simply cheaper than their current production price.
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You might find this link of interest re cleaning agents in gasoline: tinyurl.com/c5pfpvs
Page 77 onwards. Note the manufacturers which required detergency standards higher than US EPA requirements: "Top Tier" fuels. Don't think this has been debated much in EU because the EN doesn't yet include detergency/cleanliness requirements. I might be out of date on this aspect though:)
As to whether Shell is snake oil, that depends on your level of cynicism. I try to use their V Power whenever possible.
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Hi, so do I understand this correctly then, the base fuel is all the same but the additives are not all created equally. Someone mentioned that the supermarkets choose the 'cheaper' additive packages to save on cost, which would point to a difference in quality as well. Therefore, some fuels will be better than others (perhaps not over a short distance but in the long run I assume). A bit like say leather seats, both Kia and Bentley have leather seats but on close inspection there is a qualitative difference.
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"Re "all the fuel sold in the EU is to BS EN590 minimum" You may think so. There is a black market on the fringes of the EU, especially in NI, and that may be so in other areas where there are tax discontinuities. In any state in the EU, need to beware of entrepreneurial/very cheap sources. With cut-backs in enforcement, the gate guardians are in retreat. Entropy as a political aim?"
Mainland Europe uses a different standard to the UK.BS is exactly what it says it is a British Standard in Mainland Europe we use an EN number and a different recipe for diesel this can be seen in the crackers in Rotterdam.
Edited by Collos25 on 18/11/2012 at 19:38
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Not so. BS and EN are uniform on this. tinyurl.com/chkf274 Note the "BS EN590" style which might be a clue!
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If my fuel had a superior composition to that of my rivals, I'd be shouting from the rooftops to make everyone aware of this.
Of course if it didn't, I would just hire a scottish brunette to hold a conical flask of effervescent pink liquid and get her to stand next to a Ferrari...
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Essentially the fuels are the same, but the brands are differentiated, in some cases, by the additive package. If, like Shell, they shout about cleanliness internally, and the ASA haven't objected, then it seems quite likely that there is a difference. If on the other hand they are apparently indifferent to this aspect, the product is probably not a "Top Tier" fuel. One caveat: not all bases are the same. Higher octane fuels contain substances like benzene in the region of 2%, IIRC, to raise the RON (or PON) numbers. There is also the sulphur content, which for DI petrol engines, is another can of worms.
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The sulphur content of all fuel sold is now negligible. Octane rating has more to do with the branching of alkanes than additives. Tetra-ethyl lead was effective, but that's long gone.
There's nothing to stop a company boasting about "superior performance" or something equally vacuous because the term is so poorly defined as to be meaningless.
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Referring to "base petrol" I said "One caveat: not all bases are the same." Not additive related. Shell are quite specific about cleaning the internals. " formulation is designed to actively clean your engine and protect vital engine parts to help deliver more powerful performance." The issue on detergency has not been challenged by ASA.
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Can I add my vote for it's 99,9999999999% marketing blox with just the remainder being the superior HarryPotterium additives that Shall XYZ fuel delivers.
So since I;m not running a supercar I'll just stick to Asda's 'el boggo' thank you very much.
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Can I add my vote for it's 99,9999999999% marketing blox with just the remainder being the superior HarryPotterium additives that Shall XYZ fuel delivers.
So since I;m not running a supercar I'll just stick to Asda's 'el boggo' thank you very much.
Likewise.
Greenergy, in which Tesco have a huge stake, is the third largest UK business, the "UK's leading supplier of petrol and diesel" and last year supplied 10.9 billion litres of petrol, diesel and biofuel – more than one quarter of all the road fuel sold in Britain.
In July 2012, Greenergy purchased assets at the former Petroplus facility in Teesside from the joint administrators of Petroplus Refining Teesside Ltd, PwC. So they're expanding.
Even you don't fill up at Tesco, there's a fair chance you're putting in fuel from the same source as a supermarket.
The issue which is more important to me is the proper maintenance of the filling station storage tanks and associated delivery system.
Edited by BigJohnD on 26/11/2012 at 23:49
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" formulation is designed to actively clean your engine and protect vital engine parts to help deliver more powerful performance."
As opposed to all those formulations that are designed to foul up your engine and deliver less powerful performance? Shell were careful not to quantify their claims and therefore the ASA cannot challenmge the claim because it is vague and hence meaningless.
You're lead to think that Shell fuel is superior to ordinary petrol, but it could simply be that Shell petrol is superior to running your engine on nitric acid.
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For what it's worth, here are Shell's own specs for its FuelSave and V-Power diesel, compared with the EN590 standard.
Interestingly, Shell says its FuelSave will typically have a higher cetane number than V-Power.
The spec sheets also point out that 'winter' diesel comes into effect on 16th Nov, through to 15th March.
http://www.epc.shell.com/Docs/GPCDOC_X_cbe_26724_key_140003767752_201012221146.pdf
www.epc.shell.com/Docs/GPCDOC_X_cbe_26724_key_1400...f
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Hi
How do you or should you interpret the lubricity numbers - what is good and what is bad?
Lubricity EN ISO
12156-1
Microns max. 460 300
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It's a measure of scar depth-less is better. There's a lot of debate as to whether the ball bearing test is a valid measure of the lubrication of fuel pumps.
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I heard supermarket fuel sells quicker than normal forecourts, so is "fresher". Any truth in that?
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I heard supermarket fuel sells quicker than normal forecourts, so is "fresher". Any truth in that?
If you need to ask that question you need serious help.
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Fuels do have a finite shelf life, so a high turnover is no bad thing.
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Cetane number is not so important in many modern diesels as they are so sophisticated. They can have up to 6 incidents of precisely metered injection which makes them as quiet as petrol engines and not have the problems with detonation, combustion speed, the timing comprimises of old have been designed out etc...
www.youtube.com/watch?v=m7z15ZgUfJE
www.youtube.com/watch?v=uZnOcvuKmPU
Edited by Hamsafar on 29/11/2012 at 21:12
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