Originally Posted by Broxi (Post 10104655)

Sainsbury's use BP Fuel, and they sell it cheaper than any BP Filling station. :)

Tesco 99 runs spot on, I have checked the knock oth the following fuels via an Apexi Power FC and commander.

This was with No Octane booster being added.
Esso 97 RON 65 Knock
BP 97 RON 35 Knock
Sainsburys 97 RON 35 Knock
Tesco 97 27 Knock

This is adding a cannister of Regular CVL octane booster to a tank

ESSO 97 RON 45 Knock
BP 97 RON 21 Knock
Sainsburys 97 RON 21 Knock
Tesco 97 RON 17 Knock

This is adding a cannister of CVL TURBO octane booster to a tank

Esso 97 RON 32 Knock
BP 97 RON 9 Knock
Sainsburys 97 RON 9 Knock
Tesco 97 RON 6 Knock


the following was not in my car, but i witnessed the knock levels also on an Apexi

Tesco 99 RON with No Octane Booster 11 Knock Not Tested with any octan booster.
The last tst result i do not consider to be Accurate, as different engines may recieve different levels of Knock, which could be for a whole number of reasons.


But it does give a clear indication of how various fuels will behave in your car.

The Above test's were Carried out in Barnstaple N.Devon, on my RA before fitting a Simtek ECU.

every Subaru i know of that has used the ESSO Fuel in Barnstaple ends up with a Missfire that goes away when you refill at another fuel station... This is not good, I think ESSO watter down the petrol more than reccomended.

however all the other fuels are perfectly good in fact, their is a clear indication that the level of Knock is down considerably when using Tesco Petrol.
I have no Shell close hence this not being tested.
Having done the test above, I will always fill up with Tesco 99, and on advice of others Optimax 99.
I will also consider using BP if desperate, no chance will i use ESSO again.


Of course the above exercise only gives an indication on the knock level of the engine, having lo knock is obviously very Good, but the test does not show any effects that the additives may be doing If any.

Originally Posted by The Trooper 1815 (Post 10105129)

No they don't. Again a common misconception. Have a trawl about and you will see it'll be mainly JDM cars or those who specifically need to use unleaded of an Octane of 97 or above.

The new UK STi when fitted with the upgrade will have a sticker inside the fuel filler telling you what to use. Even Porsche's use 96RON unless stated other wise.

Read your user manuel and do what it says in there.

Originally Posted by chocolate_o_brian (Post 10104947)

Saying that a UK classic can safely be run on the normal 95ron fuel with no concerns unless remapped afterwards :thumb: