Found this on one of the many forums I visit, and even that didn't quote its source, but I thought it might be useful anyway to reproduce it here.

I work with petrol companies, so i'll let you into some lesser known secrets.

Super unleaded is a fine fuel, but only if purchased from reputable dealers. Esso SUPER, like BP are about the best you can buy. Supermarket stuff is just 4 star without the valve addictive, which itself is just 95 unleaded that has been octane boosted. AVOID AT ALL COSTS. Supermarket petrol is a very dirty fuel. Any engineer of their pumps will confirm that.

I have seen the results of their filters and you get everything from feathers to god knows what flowing through supermarket fuels. EVEN SAND.

All Super by law has to be 97 ron, but where its stable enough to hold higher octane, stations are able to advertise its octane as being higher sometimes.

Optimax has a variable octane rating, due to its structure its less stable, but leaves the refinery at 101 octane.

Thats the equivalent to the old 5 star for those old enough to remember it.

By the time you buy it, its closer to around 97.

This is why its octane isnt always stated.

Normal 95 or 97 fuels wont lose octane, whereas optimax does, but used fresh, its the highest octane fuel you can buy.

and

All supermarket fuels come from either the Matex or Purfleit refineries for the south east. These only take oil from the eastern block. They are most definately NOT the same fuels as ESSO and such like.

They also remix contaminations for other companies then sell the fuel on via supermarkets as well.

On average, each 50 litres brought from a supermarket will have 8% contaminates, and 9 grams of grit.

I have got 2 test tubes sitting on my desk at work of both ESSO and Tesco regular 95 for simple comparisons when arguing these points with supermarket buyers.

There is a bead in both which on the Tesco tube floats in mid suspension due to the grittiness of its petrol.

The ESSO falls straight to the bottom.

These are random samples taken every few weeks, and the results are always the same.

Q.

frightning....

guess i will stick to optimax from the very busy - 3 dels a week - 24hr shell next to my house..

never used supermartet fuel and now i know why.....

Wonder if that applies to diesel too? :confused:

But surely if the pumps have filters fitted on them, the gunk in the petrol will be removed before

it enters the tank?

Rob.

I just pointed this thread out to a colleague who runs a Civic Type-R. He pointed out this thread on one of the Type-R forums:

http://www.civictype-r.co.uk/phpBB2/viewtopic.php?t=1595

The main quotes are:

I work for an Oil Company and ALL the petrol is exactly the same. Optimax uses an additive in a small plastic bottle inside the pump injected as you fill up. The rest, Tescos, Sainsburys is, as stated before, 95RON bought from the cheapest source either from the Rotterdam Spot Market or a cut price volume deal with a Major Name. It's all the same , they sell it cheap to get you in the supermarket.....

And:

How many times have I heard the crap from some people who think that supermarket fuel is any different!?

All the fuel comes out the same whoever makes it! If it says its 95RON or 97RON thats all you have to decide....unless you want Optimax.

This comes from my M8 who works for BP and his wife who works for Fina Elf. (He runs an ATR on optimax because he has to).

They even told me that if there is a franchise garage that is too far away from its refinery, they have a deal with any of the other suppliers to supply that garage..........so you could have BP from a Texaco garage or Fina from a Jet garage and so on and so on......Its all the bloody same!

Draw your own conclusions.

Darran

I see where your coming from... Lexsport... I wasnt sure either but just had a chat with my mate Darren who runs 3 x shell garages... he confirmed the variable optimax octane...and that shell defo only comes from shell and is not ever sold to supermarkets - cos it costs more...

im sure this is one of thosr things we will never know the true answer to?

I'm not really sure if any of this is true. I know that the majority of cars in the UK will use Supermarket fuel at one time if not the majority of the time. I have noticed no difference in fuel bought from supermarkets or Jet, Shell, or BP garages (I refuse to by Esso on principle). Of course I run on Diesel but surely that makes little difference, if petrol is poor quality then so will be diesel. Even if it contains grit, or sand I suspect this would be caught by the many fuel fiters both in your car and in the pumps.

Flyingscot

Nice avatar , where is that?

Originally posted by ffelan in this post

and that shell defo only comes from shell and is not ever sold to supermarkets - cos it costs more...

Hmm...Shell garage here is the cheapest in the area by a penny a

litre! Must be to do with turnover or something I guess...

They do nice sandwiches too.

Rob.