Supermarket vs Branded Fuel — Is There Really a Difference?

Supermarket fuel is consistently cheaper than branded fuel from Shell, BP or Esso. But is it the same stuff? Does it damage your engine? Here is what the evidence actually shows.

The Base Fuel Is the Same

All petrol and diesel sold in the UK must meet the same British Standard — BS EN 228 for petrol and BS EN 590 for diesel. Every forecourt, whether it is Asda or Shell, sells fuel that meets these specifications. The base fuel typically comes from the same refineries and is transported through the same pipeline network, operated by Exolum (formerly CLH Pipeline System).

Tesco, Sainsbury's, Morrisons and Asda all source their fuel from major refineries and distribution terminals. In many cases, a Tesco tanker and a Shell tanker fill up at the same depot on the same day.

The Difference: Additive Packages

Where branded fuel differs is in the additive packages blended in at the terminal or at the refinery. All UK fuel must contain a minimum level of detergent additives, but premium branded fuels like Shell V-Power and BP Ultimate contain higher concentrations of cleaning and friction-reducing additives.

These additives are designed to keep fuel injectors clean, reduce carbon deposits, and maintain engine efficiency over time. Supermarket fuel meets the legal minimum for additives but does not typically go beyond it.

Does Supermarket Fuel Damage Your Engine?

No. There is no credible evidence that supermarket fuel causes engine damage. Every litre sold in the UK must meet the same quality standards regardless of where it is sold. The RAC, AA and most independent mechanics confirm that supermarket fuel is perfectly safe for everyday use.

Anecdotal claims about "watered-down" supermarket fuel are myths. Trading Standards regularly tests fuel quality at retail sites, and supermarkets pass the same inspections as branded stations.

The Price Difference

Supermarket fuel is typically 3 to 7 pence per litre cheaper than branded equivalents. On a 50-litre fill, that is a saving of £1.50 to £3.50 per tank. Over a year of weekly fill-ups, that adds up to £78 to £182.

The reason supermarkets can sell cheaper is straightforward: fuel is a loss leader that drives footfall into their stores. They operate on thinner margins than dedicated forecourt operators, who rely on fuel sales as their primary revenue.

Prices are illustrative based on typical UK averages. Use our comparison tool for current prices in your area.

When Branded Fuel Might Be Worth It

• High-mileage older vehicles — the extra cleaning additives in premium branded fuel can help maintain injector performance in engines with significant mileage.
• Performance or turbocharged engines — some manufacturers recommend higher-octane fuel (97+ RON), which is only available as branded premium.
• Occasional deep clean — some mechanics suggest running a tank of premium branded fuel every few thousand miles to help clean the fuel system, though the evidence for this is anecdotal.

The Verdict

For the vast majority of UK drivers, supermarket fuel is the smart choice. It meets the same quality standards, is significantly cheaper, and will not harm your engine. The savings of £80 to £180 per year are real and meaningful.

If you drive a high-performance car that requires 97+ RON, or you have an older engine with injector issues, branded premium fuel may offer marginal benefits. For everyone else, fill up at the supermarket and use the savings for something better.

To find the cheapest supermarket fuel near you, use our price comparison tool. For more on saving money at the pump, read our 15 ways to save money on fuel or see which UK retailers are cheapest in 2026.