Found this on another forum.
Quote:
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 additive, 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 octiane.
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.
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.
Texaco is a subsidary of ESSO and both use the same petrol.
There are basically 3 companies which supply fuel to the UK. ESSO, BP, AND SHELL.
Each sells to all the other names you find.
JET, FINA, Q8 and a few other smaller outlets all use SHELL.
TEXACO and TOTAL use ESSO,
Supermarkets use Eastern Block fuels, which are primarily designed for the 91 Ron continent market.
These are upgraded in the UK to UK specs by using Butane gas.
Hence to avoid.
BP Ultimate is just its old Super grade cleaned up a bit.
IE. It goes through another filter at the refinery.
Not a bad fuel though, second only to ESSO in quality.
Its Diesel is the best in the world for all you Diesel owners.
OPTICRAP. Need i say more. All grades supplied by Shell.
Might as well fill from your local FINA station and pop a bottle of Halfarts octane super duper booster plus in.
ESSO 95 and 97 = If you want every pennies worth in quality petrol, look no further.
Get it at your local TOTAL, TEXACO or ESSO now :beer:
