Supermarket Fuel or Branded Fuel: Does It Matter for Your Car?

For most cars, no. All petrol and diesel sold in the UK has to meet the same national standards, so supermarket fuel is not dirty or harmful. The differences between brands are mainly in the additive packs. Premium fuel is worth it if your handbook asks for it, but servicing matters far more than where you fill up.

Is supermarket fuel worse than branded fuel?

Petrol sold in the UK must meet the BS EN 228 standard and diesel must meet BS EN 590, wherever you buy it. Much of it comes from the same refineries and terminals. What varies is the additive package blended in, such as detergents that help keep injectors and valves clean.

For an ordinary car in good condition, used for commuting, the school run and motorway trips, supermarket fuel is fine. You can also mix brands freely.

Is premium petrol worth paying for?

Standard unleaded is usually 95 octane (RON) and premium or super unleaded is usually 97 to 99. Higher octane resists knock, which matters for engines designed to use it.

• If your handbook or fuel flap says 98 or 99 RON, use it. Many performance and some turbocharged engines are set up for it.

• If your car is designed for 95 RON, premium fuel is unlikely to make a noticeable difference to performance or economy, and rarely pays back its higher price.

• Older or E10-sensitive cars may need super unleaded because it is usually still E5.

What about E10 petrol?

Standard unleaded in Great Britain is E10, which contains up to 10% ethanol. Most modern petrol cars are approved for it. Some older cars and classics are not, and E10 can give slightly lower fuel economy than E5. Our E10 petrol guide explains how to check your car.

Is branded or premium diesel better?

Standard diesel from any reputable forecourt is fine for everyday use. Premium diesels carry stronger detergent packs, and some owners of older or fussy diesel engines find they run more smoothly on them. They are not a fix for a blocked particulate filter, which needs regular longer runs and sometimes workshop attention. See our guide on DPFs and other engine issues.

What matters more than which fuel I buy?

• Using the correct fuel type and octane for your car

• Regular oil and filter changes on schedule

• Giving diesels a regular longer run

• Dealing with warning lights and rough running promptly

If you want to cut what you spend on fuel, our guide on spending less on fuel has practical tips.

Common questions

Can I mix supermarket and branded fuel?

Yes. As long as it is the right fuel type and octane, mixing brands does no harm.

Will premium petrol make my car faster?

Only if the engine is designed to use higher octane. A typical 95 RON car is unlikely to feel any different.

Can supermarket fuel damage my engine?

Not if it is the correct type for your car. Engine problems usually come from poor maintenance, the wrong fuel such as petrol in a diesel, or an underlying fault.

Car running rough or using more fuel than it should?

Our service centre in Barnsley, South Yorkshire can check it over. Our labour rate is £80 per hour plus VAT, and our menu prices include VAT. Call Customer Care on 01226 574321. If it is time for something more economical, browse the cars in stock at anycolourcar.com.

Updated October 2026.