[Redtoy]

Hi I've steered clear of shell since their denial of problems caused in Nigeria and bp since environmental disasters in gulf of Mexico. This is purely subjective of course and it seems that using these companies' fuel may be unavoidable while running a car. I usually use supermarket fuel but it all comes from the same place, right?
Now my local supermarket is more expensive than some branded stations. I couldn't use a shell branded stations for sure but is this just academic in the end? Does anyone remember what happened to Ken Saro-Wiwa in Nigeria or am I the only one?

[olduser]

In a lifetime of motoring I have never been loyal to a brand.
Lowest price has always worked for me.
Claims for higher mileage with different grades are difficult to prove or disprove so I buy normal grade.
Higher mileage is easily achieved by planning your driving, good maintenance, and keeping the tyres at the correct pressure.

[Rolebama]

Most petrol comes from the same refinery. It is down to the retailer what additives are added. Supermarket fuel may have an additive for easy cold starting, and the brands may have additives for better mpg, cleaner engine, better anti-knock etc, but essentially the basic petrol all has to pass the relevant standards for sale. Generally, it is the additives which dictate the pump price. Although having said that, location seems to be just as relevant.

[Mark07]

Originally Posted by Rolebama

[...] Although having said that, location seems to be just as relevant.

I've seen significant price differences from town-to-town in my region.

In my unscientific observations, I've noticed that supermarkets tend to keep their prices consistent with each other, but disregard outliers e.g. independent petrol stations... though there aren't many of them left.

For more accurate fuel prices news and trends, take a look at RAC's Fuel Watch.

[Drivingforfun]

My experience is similar to Mark's

Supermarkets are all in competition but specialist fuel companies (BP, Shell etc.) price themselves a bit higher, perhaps as people see it as a premium product?

I think it's mostly charging what they can - there's a well-to-do village near me with a single, independent, garage which routinely charges 20p above the "going" price; while it's only about 5 miles to the nearest Tesco, it's a 10-15min drive along windy narrow roads and I guess some of the middle class people in the village are happy to pay for the convenience

[Rolebama]

Within a 15-minute drive, I have 3 Texaco, 3 Shell, 1 BP, plus 4 others I am not sure of. Out and about on Weds I noted they are all around 136/7.9 per litre. Wednesday morning I paid 137.9 at Sainsbury's Biggleswade.
The BP is on the very busy rush hour rat-run and the most expensive in the area.

[olduser]

Originally Posted by Drivingforfun

My experience is similar to Mark's

Supermarkets are all in competition but specialist fuel companies (BP, Shell etc.) price themselves a bit higher, perhaps as people see it as a premium product?

I think it's mostly charging what they can - there's a well-to-do village near me with a single, independent, garage which routinely charges 20p above the "going" price; while it's only about 5 miles to the nearest Tesco, it's a 10-15min drive along windy narrow roads and I guess some of the middle class people in the village are happy to pay for the convenience

I have asked friends who buy from expensive outlets, their response is usually, they must have the best for their car or their car needs the best fuel.

I found this list of Fuel additives:

"Petrol additives are chemical compounds added to fuel to enhance its performance, improve engine efficiency, and minimize potential problems. They serve various purposes, and their types can be categorized based on their functions. Here are some common categories and their uses:

1. **Detergents**: These additives help clean the fuel system, including fuel injectors and intake valves, preventing carbon build up and ensuring optimal engine performance.

2. **Octane enhancers**: They increase the octane rating of petrol, allowing the fuel to resist knocking or pinging during combustion, which is crucial for high-performance engines.

3. **Corrosion inhibitors**: These additives protect metal parts of the fuel system from rust and corrosion, extending the lifespan of the engine components.

4. **Stabilizers**: Fuel stabilizers help prevent the breakdown of fuel, especially in petrol that may sit for extended periods. They can prevent issues like varnish formation.

5. **Conductivity improvers**: These additives enhance the electrical conductivity of the fuel, improving combustion efficiency and reducing emissions.

6. **Fuel moisture dispersants**: These help manage water within the fuel tank, preventing phase separation and rust that can result from water contamination.

7. **Anti-knock agents**: Such as tetraethyl lead (in some regions), these agents help improve performance by reducing engine knock, although leaded petrol is now phased out in many places due to environmental concerns.

8. **Emissions reducers**: These additives help lower the emissions produced during combustion, contributing to compliance with environmental regulations.

9. **Cold weather additives**: These are used to improve fuel performance in cold conditions, preventing issues like gelling and ensuring proper flow through fuel lines.

Overall, petrol additives play a significant role in enhancing vehicle performance, efficiency, and longevity, while also helping to meet environmental standards".

I would think that list is old, I think, with fuel injection, and the antipollution requirements, carbon build up should have just about disappeared.

The fuel additives are not in the British Standards for fuel, they are concerned with the energy content, viscosity, flash point, octane rating, and physical properties.
As I understand it, any of the additives in the list above are added in the tanker making the delivery to the retail outlet.

I don't recall ever seeing any confirmation or denial that the above cocktail is or is not in all fuel on sale in the UK, with the exception of higher mileage additives, where these are used to justify a higher price.

[Drivingforfun]

I often notice the additives referred to by generic adjectives like "detergents" or "emissions reducing" ... and wonder if a manufacturer ever disclosed exactly what the compounds* are actually made of?? i.e. some kind of chemical structure of atoms, so that the clever people out there with the adequate grasp of chemistry can scrutinise it and explain to the rest of us whether or not it's snake oil??

*I'm probably not using the right scientific words but hopefully you know what I mean

[olduser]

Originally Posted by Drivingforfun

I often notice the additives referred to by generic adjectives like "detergents" or "emissions reducing" ... and wonder if a manufacturer ever disclosed exactly what the compounds* are actually made of?? i.e. some kind of chemical structure of atoms, so that the clever people out there with the adequate grasp of chemistry can scrutinise it and explain to the rest of us whether or not it's snake oil??

*I'm probably not using the right scientific words but hopefully you know what I mean

Whilst I am no chemist I have, 'played' at doping fuel first in model aircraft engines and later in cars.
The first common additive would probably Alcohol or Nitrate these provide Oxygen and some extra energy, extra Oxygen means the engine can run on a richer mixture giving more power. Alcohol also benefitted combustion. (less of a bang more of a push)

Benzene helps with anti nock (raises the Octane number) but Tetra Ethyl Lead (lead) gave a dramatic control over Octane value enabling much higher compression ratios, resulting in higher power and efficiency but above all it was cheap.
Lead is not used these days, due it's detrimental effects on humans.
I think Benzene has replaced Lead, but Benzene is carcinogenic so other ways of raising Octane value are being looked for.

Detergents were supposed to keep Carbon deposits down in engines, in the days of Carburettors most engines showed plenty of Carbon in the combustion chamber when opened up, it could, and often did get so bad it affected the running of the engine. (caused nocking, preignition, the carbon stayed hot enough to fire the mixture early)
The source of Carbon was oil getting past the piston rings, modern engines have better cylinders, piston rings, and crankcase ventilation and of course better oil.

Adding Oxygen can be looked at as extra power or better mileage therefore lower emissions.
Higher Octane again can be said to give higher power or lower emissions if the power is not used.

That's about the limit of my experience in this field.

In summery, I doubt that any of the usual additives fall into the' 'snake oil' category most are expensive so some may be used in such small amounts they have little effect.
But Octane enhancers have to produce a Octane number approved by BSI. (95 or over)

[Rolebama]

I think there is an element of snake oil involved. Back in the 80s we had Shell selling something that caused almost all BL cars and the smaller Ford engines to pink. The only thing we could do was retard the timing to stop the pinking, which led to a loss of power and consumption, increasing pollution.
As an aside to this I filled my diesel car with Formula V. I had read a couple of reviews saying it improved mpg. Not in mine though. I lost about 1 mile per litre after driving off with a much lighter wallet.
My current car drives fine with E10, and there's no way am I forking out for E5 at the additional cost per litre.