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Old 06-09-2005, 03:57 PM   #1
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Shell petrol versus supermarket

I try to put Shell unleaded in my R129 (which only does about 3k miles a year), but my VW Sharan V6 generally gets filled up at Sainsburys (which is cheap and much more local).

Last week though I put a tank of Shell petrol (regular unleaded, not Optimax) in the Sharan before towing the caravan 200 miles to Stoneleigh and back. Much to my surprise there was an immediate and noticeable improvement in both performance and economy! Less gear shifting required on the motorway (I doubt I'd have noticed this if I hadn't been towing though), and total fuel consumption (from the computer) of 16.9 mpg instead of the 15 or so I'd normally get in similar traffic conditions. This was despite having the climate control blasting away all the time (very hot weekend).

Whilst I accepted that there were probably long term benefits in using 'branded' fuel I wasn't expecting any noticeable difference on the road!

PS my R129 handbook just says to use "minimum 95 RON unleaded" fuel, would Optimax be a good or bad idea (M119.982 engine)?
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Old 06-09-2005, 04:05 PM   #2
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Hi,

It seems logical to me that there is a better chance of getting good fuel from Shell, Esso, BP etc. because they make the stuff. The supermarkets buy on the spot market as cheap as possible. Invariably they will get 'the bottom of the barrel' fuel with higher water content and lower octane/cetane.

In my garage often I see the problems of high water content with cars playing up. The lower octane/cetane count has a direct effect on the efficiency of the engine. Hence better fuel economy.

I wouldn't fill up at the supermarket. I've seen too many problems.

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Old 06-09-2005, 04:09 PM   #3
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I have tried diesel from supermarket and BP/Shell (branded) and it has made no difference what so ever to the fuel consumption or even the engine noise (which some claim it quitens down with branded fuel). Personally, I think that it is all psychological...
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Old 06-09-2005, 04:29 PM   #4
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Quote:
Originally Posted by Flash
Personally, I think that it is all psychological...
Not in my case, I wasn't expecting any difference. But as mentioned I doubt I'd have noticed without 1.5 tonnes of caravan on the back, having to shift down for hills is a pain when you're on cruise control with a manual gearbox.
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Old 06-09-2005, 04:32 PM   #5
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Do a search on Optimax . The debate has raged on here for years!
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Old 06-09-2005, 04:58 PM   #6
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I think there could be an argument for petrol being different. Petrol is only about 40% actual petrol the rest is additives, so it stands to reason that some may be blended better than others.

Don't know about diesel, it really is mainly oil. Obviously cetane improvers will help but not sure about much else??

I've personally never noticed any real difference.
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Old 06-09-2005, 05:00 PM   #7
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Do a search on Optimax . The debate has raged on here for years!
Just what I was thinking G - and it's one of those where there is only personal experience - no real conclusive evidence one way or the other. So much mus depend on your car as well. I know I noticed not one jot of difference with Edna on "quality" fuel, only the dent in the plastic card

I vaguely remember Sainsburys being praised for their petrol as it is up to the standard of Shell, Esso, BP etc. But that could have just been some bizarre dream
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Old 06-09-2005, 05:52 PM   #8
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Quote:
Originally Posted by pammy
...But that could have just been some bizarre dream
Wow that would be bizarre, dreaming about Sainsbury's petrol

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Old 06-09-2005, 06:03 PM   #9
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Wow that would be bizarre, dreaming about Sainsbury's petrol

S.
indeed but who knows what G & T + Baileys can do
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