This is a copy of an email that was sent to us at work.(Email edited)
Comments gents

From: Debbie Crawford/UK/Tesco [mailto:debbie.crawford@uk.tesco.com]
Sent: 15 March 2004 23:31
To: mango@locostbuilders.co.uk
Subject: Tesco fuel quality
Hope the following helps.
All fuel supplied to Tesco meets the relevant Bristish Standards as well as
the Government Fiscal Specification for Ultra low Sulphur Fuels.
As part of our supply agreements, all unleaded and Diesel fuel contains a
detergent additive, as recommended by most leading motor manufacturers,
meeting their performance requirements. These additives are supplied by the
oil companies.
There is no such thing as "Supermarket" fuel - Supermarkets do not own or
run oil refineries. All fuel is supplied by either major UK refiners or
major European refiners.
To ensure ongoing quality, we independently test forecourt samples to
ensure compliance with the product specifications and ensure there is no
contamination.
Tesco is the biggest independent retailer in the UK with a market share of
about 12%. We therefore sell 1 in every 8 litres of fuel in the UK,
equating to around 2.5 to 3 million customer a week and growing.
Why Pay More?
---- Disclaimer ----
This is a confidential email. Tesco may monitor and record all emails. The
views expressed in this email are those of the sender and not Tesco.
Tesco Stores Limited, Tesco House, Delamare Road, Cheshunt, Herts, EN8 9SL:
company number 519500.
_____________________________________________________________________

[Edited on 1-12-05 by mangogrooveworkshop]

Not sure what your point is? Oil companies supply fuel to supermarkets, and Shell (and presumably others) might produce different blends/additives for sale in their own filling stations?

It doesn't say that what Tesco sells is the same as Optimax, if that's what you're implying

Hmmmm,

Did anyone not see the (IIRC) 5th Gear petrol test on tv a couple of weeks ago?
They were testing Shell Optimax, BP Ultima and supermarket fuels against each other, for different applications.
This followed Hellfires excellent thread from a couple(ish) of weeks previous, to the programme....

Fozzie

But did they test Tesco's 99 Ron stuff ?????? Makes me missus's Focus quicker !!

Jason

Yup, I am sure they did Jason!....
Shell Optimax came significantly out on top (rolling road tested), giving more bhp (8-10), and more torque, over the supermarkets 'best'.
Ultima (BP) was just a bit better than the supermarkets 'best'.
Verdict....

1 Shell Optimax, by far!
2 BP Ultima
3 Supermarkets 'best' (only just behind BP)

Fozzie

Oh ok, thought they only checked the basic UL

Jason

No, they did the supermarket 'best', because they were testing the 'best' from BP and Shell.
It would have been a pointless exercise to test against ordinary UL.

Copied from 5th gear , doesn't really say other than Ordinary unleaded ?????
Jason

http://fifthgear.five.tv/jsp/5gmain.jsp?lnk=601&featureid=143&pageid=272


Renault Clio
First up was the new Renault Clio, an ordinary family runaround.


On ordinary unleaded the Clio produced 81 bhp.
On BP Ultimate, it produced 81 bhp.
And on Shell Optimax, it was, you guessed it, 81 bhp.

So it seems an engine geared towards economy simply can't take advantage of the extra performance fancy fuel can offer.

[Edited on 1/12/05 by Deckman001]

That was only ONE of the tests!..In fact the first test, there were about 3 different tests IIRC

And yes, I stand corrected on the supermarket 'unleaded' bit, but we did see the programme, and we both remember them saying the supermarkets 'best'.
On the link you posted, look at pages 3-4 inclusive

[Edited on 1/12/05 by Fozzie]

[Edited on 1/12/05 by Fozzie]

Forgot to say, (but did on t'other thread), that we tested these fuels ourselves a few years ago now.
In my modern tin-top the optimax and ultima, made no diference what so ever over the ordinary unleaded.
But in our race engines (the oldies), and in the fozzmobile, Optimax was found to be better by far....In Our Experience of course!

Basic fuel is distilled by the refinaries and is loaded into trucks for many branded forecourts from the same tank. Fuel additives are mixed into the fuel depending on the brand. These include benzine for unleaded or sodium for LRP or lead for leadded. They can include detergents and other fuel improvers. Supermarkets are said to have fewer additives to keep the cost down and so will be "less good" over time. Some people suggest that your engine won't cake up in deposits too quickly so occasional use of cheap fuel will do no harm.

The other side of the arguement is that some fuel is more distilled than others. Sure, they all meet the minimum standards but that doesn't say much. Some fuel is fairly pure octane / iso-heptane. Other fuel is made from higher fractions of crude which is "cracked" using a catalyst into ligher hydrocarbons. Low grade fuel can be treated with octane boosters to make up the octane level. Many types of fuel may be 95 RON. that is octane (100 RON) plus other lower RON stuff such that the average is 95. I would guess that cheaper fuels more lower grade stuff in there than expensive fuels.

Which story is right? I don't know. Perhaps the truth is a bit of both.

friends that have had imprezas and audi rs6 say the type of fule they use has a big effect on power. Unless run on Optimax, the impreza was several tens of hp down - im guessing the engine efi detected lack of octane / whatever, and reduced power for safety.

atb

steve

If your cars ecu can adapt to the octane rating of the fuel then you will notice a performance difference but if your ecu doesn't you won't.
I could certainly feel the difference in my Impreza and if you didn't use all the performance it used to do 20-30 more miles on a tank of Optimax compared to 95 unleaded, whereas it made bugger all difference in my wifes 206.