Supermarket Fuel vs Branded Petrol: Is There Really a Difference?
Supermarket petrol can be 5–8p per litre cheaper than branded forecourts — but drivers often worry about quality. Here's the definitive answer.
The Short Answer
Standard supermarket petrol and diesel are essentially the same quality as standard branded fuel. Both must meet mandatory UK and EU standards. The main difference is in additive packages — but for most drivers in standard cars, these make little practical difference. Fill up at the cheapest station near you.
The Legal Standards: Why Quality is Guaranteed
All petrol sold in the UK must comply with BS EN 228 (for unleaded petrol) and all diesel with BS EN 590. These are European standards specifying minimum octane ratings, maximum sulphur content, energy density, and other quality measures.
Every forecourt — whether it's Asda or Shell — sells fuel that has passed the same quality tests. The Office for Product Safety and Standards (OPSS) regularly tests fuel at forecourts across the UK. Non-compliant fuel is rare and not specific to any type of retailer.
How Supermarket Fuel Gets to the Pump
UK fuel comes from a handful of refineries and is distributed through a shared network of pipelines and storage terminals. It's entirely normal for the "base fuel" at a Tesco forecourt to have come from the same refinery batch as the fuel at a nearby BP station.
The differentiation happens when branded forecourts add their proprietary additive packages — cleaning agents, friction modifiers, and corrosion inhibitors. Supermarkets may use different (typically simpler) additive packages or the base fuel as-is.
Premium Fuels: Shell V-Power, BP Ultimate, Esso Synergy
Branded forecourts sell two grades: standard (95 RON) and premium (97–99 RON). The premium grades — Shell V-Power, BP Ultimate, Esso Synergy Supreme — contain significantly enhanced additive packages claiming to:
- •Clean fuel injectors and intake valves
- •Reduce engine friction and wear
- •Improve combustion efficiency
- •Provide better cold-weather performance
Independent testing by Which?, Auto Express, and others has found marginal improvements in fuel economy (typically 1–3%) and some cleaning benefits after extended use. The problem is that at 15–20p/litre more, you'd need to see a 12–15% improvement in fuel economy to break even — which never happens.
Supermarket vs Branded: Price Comparison
| Forecourt Type | Typical premium over cheapest | Extra cost per 50L fill |
|---|---|---|
| Cheapest local supermarket | Baseline | Baseline |
| Average supermarket | +1–3p/litre | +50p – £1.50 |
| Independent forecourt | +3–8p/litre | +£1.50 – £4 |
| Branded forecourt (standard) | +5–10p/litre | +£2.50 – £5 |
| Motorway service station | +15–25p/litre | +£7.50 – £12.50 |
| Premium fuel (V-Power etc.) | +15–20p/litre | +£7.50 – £10 |
Approximate figures. Use Fuelr for live prices in your area.
When Is Premium Fuel Worth It?
Premium fuel may be worth considering if:
- •Your car manufacturer specifically recommends 97+ RON fuel (check your handbook)
- •You drive a high-performance or turbocharged engine with high compression ratios
- •You drive a classic or older car with potential fuel system deposits
- •You want to occasionally "treat" your engine with a cleaning additive dose
For the vast majority of drivers with modern standard cars: use the cheapest E10 you can find and pocket the difference.
Frequently Asked Questions
Will supermarket petrol damage my engine?
No. All petrol sold in the UK must meet the EN 228 standard (for petrol) or EN 590 (for diesel), regardless of where it's sold. Supermarket fuel meets exactly the same mandatory quality and octane requirements as branded fuel. There is no credible evidence that standard supermarket fuel damages engines in normal use.
What is Shell V-Power and is it worth buying?
Shell V-Power is a premium 99 RON petrol with a proprietary additive package that Shell claims reduces friction in the engine and cleans fuel system components. Independent tests have shown modest fuel economy improvements in some engines. However, at 15–20p/litre more expensive, most drivers on standard cars won't see enough improvement to justify the cost. For high-performance or turbocharged engines, the benefits are more noticeable.
Is BP Ultimate better than regular petrol?
BP Ultimate is BP's premium fuel grade (97 RON or higher) containing cleaning detergents and friction-reducing additives. Like Shell V-Power, it may provide modest benefits for some engines over extended use, particularly in cleaning intake valves and fuel injectors. For most drivers, the savings from using standard E10 significantly outweigh any benefits.
Can I mix supermarket and branded petrol?
Yes, completely safe. Petrol is petrol — mixing fuels from different forecourts causes no harm whatsoever. The only consideration is octane rating: don't mix E10 (95 RON) with Super Unleaded (97+ RON) if your car specifically requires high octane fuel, though even that is safe in practice.
Do supermarkets buy fuel from the same refineries as BP and Shell?
Often yes. The UK fuel supply chain is complex — refineries produce fuel to EN 228/EN 590 standards, and it's distributed via shared pipelines and storage facilities. It's common for fuel at Tesco to have come from the same refinery batch as fuel at BP, the only difference being the additive package injected at the forecourt.
Which supermarket has the cheapest petrol?
It varies by location and day. Asda, Tesco, and Morrisons are consistently among the cheapest, often competing within 1p of each other. Prices are updated throughout the day, so using Fuelr to compare live prices at your nearest supermarkets is the best way to find the cheapest on any given day.
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