GolfGTIforum.co.uk
Model specific boards => Golf mk7 => Topic started by: e.l.s on 17 October 2013, 22:10
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Hi all
Sorry if this has been covered already, I did search but couldn't find the answer
Which diesel would you recommend we use in our new gtd? We've never had a diesel car before and don't know if it's worth paying more for the premium options
Diolch/thank you :smiley:
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use anything but morrisons supermarket diesel.
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There was a discussion somewhere around here
http://www.golfgtiforum.co.uk/index.php?topic=257669.msg2366103#msg2366103 (http://www.golfgtiforum.co.uk/index.php?topic=257669.msg2366103#msg2366103)
I find with my MK6 GT Diesel - the 'super' stuff doesn't make a lot of difference, however it does in the wife's Zafira
Hope that helps :)
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use anything but morrisons supermarket diesel.
This and supermarket fuels in general. Stick to the branded forecourts. The premium diesel isnt really worth the extra on new cars
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What's wrong with Morrissons? Mine uses Texaco fuel. Never used it myself, but I have used a proper Texaco station without ill effects.
I have been using Shell V-Power for 2 tanks now and it does not live up to expectations for me. I thought the purity would result in fewer regens (which kill mpg) to counteract the fact that it is less dense than regular diesel (shorter hydrocarbon chains I would guess that is) and has an average Cetane number of 52, vs standard Shell which is 56. In short it is less potent and contains less chemical energy per litre. Many people here reporting poor mpg have been using Shell V-power, whereas those using regular Shell (or other diesel) have been reporting far better (around 10% better) mpg.
Historically, in owning 6 previous VW TDIs - they seem to run best on Shell or BP, not so good on Esso.
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A little while ago there was a good article on here about octane in fuel and why for most of us it's a bit of a myth that paying for higher octane translates to any benefit to the car.
Does a similar article exist for fuel? Why should we avoid the cheap stuff and what's better about the branded forecourts?
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morrisons allegedly use a higher amount of bio additives than other forecourts and vw don't like bio additives.
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Morrisons use up to a maximum of 5% ethanol, which is quite normal, and meets EN590 standard.
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A higher Cetane value makes the diesel fuel combust more readily when mixed with air and compressed. You are likely to get a more complete burn with a high Cetane value fuel because ignitions starts earlier in the compression cycle. There is always the risk of the molecules at the higher end of the chain length range not completely combusting if ignition starts later in the compression cycle due to a low Cetane rating, so it makes sense to up the Cetane level – to a point. You don’t want the fuel so volatile that it’s like petrol. Cetane rating of 56-58 is considered optimum.
Normal Diesel is a mixture of Hydrocarbons varying from 8 to 21 carbon atoms in length. I suspect that V-power (with a proportion made from gas to liquid process for higher purity) ends up with a lower average hydrocarbon chain length because creation of longer carbon chains than the starting material is precise, hence the lower density compared to regular diesel.
In effect, V-power has less energy per litre to liberate under combustion (as does Petrol – it contains about 12% less chemical energy than Diesel), but the relative purity of the stuff as well as the added lubricity components is supposed to make the most of what is there under combustion and so level the playing field. If my car ends up with more mpg when I switch to normal Shell then I would definitely say that is not the case.
Difference between branded fuels and supermarket fuels isn’t the fuel itself, but the additive packs – the stuff like the added detergents which help keep your engine clean, some other additives (mainly alkyl nitrates) which lower the temperature and pressure conditions required for combustion (by increasing Cetane number). You tend to get a better set of additives in the branded forecourts.
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TDIs don’t like bio additives. They will tolerate no more than 5% addition (EN390 standard?)– on the continent when Bio additions are generally higher than in the UK, you really have to watch out for bio content of diesel when filling up. Biodiesel rots many rubber-like compounds more commonly used on newer diesel engines (which is why you can put it in your ancient Audi 100 diesel, but not newer VAGs).
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http://www.golfgtiforum.co.uk/index.php?topic=256725.0
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Thanks so much for your replies, they're very helpful. We tend to not buy supermarket fuel anyway, and will definitely avoid in future :smiley:
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There is no difference between supermarket diesel or any "branded" standard diesel. They all come from the same refineries, pretty much. Ineos for example, only one example of a fuel refinery. The "special" fuels that are sold generally have additives added after the basic refinement has been done.
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totally disagree with you. shell, bp, esso don't put the same level of bio additives in at the forecourt than morrisons do. even the master tech at local dealership said to avoid morrisons as they'd had quite a few cars in that weren't running right. everyone is entitled to use whichever fuel they want mind just I won't be going anywhere near a Morrison's forecourt.
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It depends if you have worked in the industry of course and with the manufacturers of fuel ... I remember my dad and his mates in the 70's talking about Jet, and how it was substandard fuel. It wasn't and the same is true today's itch supermarkets , fuel is processed at the same facilities for all sellers. A lot is spot purchased from refineries that have an excess of production versus another refinery , buyers can purchase from anywhere and the various companies will arrive in their branded vehicles to collect . However, you are correct in that we all have a choice, I use BP or Sainsburys for my Nectar Points :grin: