Watered petrol

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allan horsfall
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Watered petrol

Post by allan horsfall »

Gentlemen,

I was chatting to a mate of mine the other day who told me about his brother in laws experiments with petrol ( he's a motorbike fanatic ) and was concerned about the amount of rusting he finds internally when his bikes are put away for the winter. He bought a testing kit which required him to put half a litre of water with soluble additive into 5 litres of petrol. It was then left for a period of time for the water to seperate from the petrol, when he opened the drain tap he got 1 litre of water out. ie 1/2 a litre more than he put in, the petrol was bought from a supermarket.
He tried the same experiment with petrol from various sources and found premuim brands ie. Shell, BP, Elf etc. were OK, supermarkets were not.

Some years ago I had a conversation with a guy who reckons he got 5 miles to the gallon more driving from Suffolk to Cornwall than on the return journey. For the trip down he filled up at his local Elf station and for the return at a supermarket. I argued that as supermarkets buy their petrol on the Rotterdam Spot Market it should be the same petrol? Im now wandering if the supermarkets buy it watered down to make it go further.
Go figure!!!!

Allan
catsx11
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Post by catsx11 »

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Roger King
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Re: Watered petrol

Post by Roger King »

Some of this may be explained by the devil's own additive, ethanol. This is notorious for separating out water in petrol, which is the main reason it is literally added to the full tanker as it leaves the depot on the way to the filling stations. The longer this stuff is in with petrol, the more water it will produce. It also explains why a classic or other car that tends to sit for long periods of time (e.g. over-wintering) can have big problems with water layers forming in their fuel tanks producing corrosion etc. You can get winter stabiliser, but I don't know how effective this is - I try to keep the tanks as empty as possible over winter so the first fill will dilute any ethanol byproducts, and I avoid any supermarket fuel and 95 (which is all at least 5% ethanol) in general.
This issue is a major factor in my choice of superunleaded as all information I see points towards that containing less ethanol.
It's time governments woke up to the harm done by the pointless addition of this environmentally-damaging stuff to our fuel merely on political grounds.
Paul Blore
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Re: Watered petrol

Post by Paul Blore »

There are countless factors that could explain the 5mpg difference in the two journeys so I personally wouldn't take that as conclusive evidence, but the water is interesting.
So much of this is anacdotal, so it is difficult to get real information.
One factor in favour of the supermarkets is that they generally get through their fuel far quicker than the main brand stations. Therefore, if the water separates out over time and accumulates at the bottom of their tanks, which is where the pickups are, it could be argued that supermarkets are the best place to get your fuel. Unless you can time your fill up just before or just after the tanks are filled when either all the water has already gone, or it hasn't yet started to separate.
Roger's point about the fuel left in tanks over winter is very valid though. The tank on my Cobra is stainless, so that isn't a problem, but the Ferrari is steel and it would be interesting to know what they're (there's two of them) like inside.

Paul
allan horsfall
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Re: Watered petrol

Post by allan horsfall »

High guys,

I gather another problem resulting from this fuel is being experianced with motor mowers, it seems most of the carbureters used on them these days are made in China and the aluminium castings are not that good, that is to say pourus. When the mowers are removed from the shed in the spring they dont work, because many of the non-aluminium carb parts are seized up. Apparently this is a known major problem, again put down to the water in the fuel?.
The problems all seem to stem from cheap fuel, I guess you get what you pay for.

Paul, regarding the MPG difference I have to say this guy was Anal about his data, I should perhaps have mentioned that the debate took place at a Mensa meeting, and if that wasn't bad enough he is definately on the autistic spectrum, jokingly I even sugested that Cornwall was down hill from Suffolk!!!

Allan
allan horsfall
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Re: Watered petrol

Post by allan horsfall »

Alan,

I have to say I dont know, my expertise in the oil patch was more downstream, and even in R&D I didnt really get into the petro/chem side, but I would assume its emulsified and held in suspension to some extent, the mechanism Im not sure of, but I would assume it would have to be a chemical process rather than physical.

Allan
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Roger King
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Re: Watered petrol

Post by Roger King »

The damage to aluminium parts is caused by ethanol - if you want to know more, go to the FHBVC website and look under 'fuels'. A lot of research links there. Aluminium and ethanol do not mix - another good reason for using superunleaded.
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peterc
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Re: Watered petrol

Post by peterc »

When a reader writes in with an engine problem the Saturday Telegraph motoring section recommends avoiding super market petrol on the basis that it doesn't have the quality/ additives of the major brands. On that basis I always use a busy / well used Shell outlet in the expectation that the fuel hasn't sat around for too long.
I checked out the Shell web site they quote 5% ethanol for both 95 and 98 octane fuels and don't state it's a minimum.
The other comments above are both interesting and worrying.
Peter C
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Re: Watered petrol

Post by Paul Blore »

According to the Esso website, their Synergy Supreme+ 97 super unleaded contain no ethanol, unless you are in Cornwall, Devon, Teeside or Scotland.

Paul
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Roger King
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Re: Watered petrol

Post by Roger King »

peterc wrote:I checked out the Shell web site they quote 5% ethanol for both 95 and 98 octane fuels and don't state it's a minimum.
The 5% figure isn't a minium, Peter - it's a maximum. If they go over 5% they are required by law to mark it as 'containing 5% ethanol' - i.e. they have to warn us. Why? - you may ask.
At the moment, anything with over 5% ethanol has to be marked as 'E10', which you will have seen in mainland EU countries where it is commonly available. Put this in one of our cars at your peril - even my 2001 BMW has stickers on it telling me not to use E10, and it has a relatively modern fuel system. Zinc, aluminium etc. is not stable in E10 - so goodbye any US carburettor or Weber I have ever seen.
Best do as Paul has noted and stick with the better quality 'super' brands such as Esso and Shell. Unless things have changed very recently Shell Nitro+maxv-superwhatever contains little, if any, ethanol.
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