"I only use Shell because supermarket fuel ruined my mate's engine."
"Premium fuel gives you way better MPG."
"Tesco petrol is basically water."
You've heard the claims. Maybe you've even repeated them. But is there any truth to the idea that branded fuel is better than supermarket fuel?
Let's look at the facts.
The Short Answer
For most drivers, there is no meaningful difference. Supermarket fuel meets exactly the same legal standards as branded fuel, and your car will run just fine on it.
What's Actually in Your Fuel?
All petrol and diesel sold in the UK must meet British and European standards (BS EN 228 for petrol, BS EN 590 for diesel). This applies to every forecourt.
The base fuel often comes from the same refineries. The difference is in the additive packages – detergents and chemicals designed to clean injectors and protect engine components.
Premium brands like Shell, BP, and Esso invest heavily in proprietary additives. Supermarkets use more basic, generic packages.
Does It Actually Matter?
For the vast majority of drivers, no. Modern engines are incredibly robust and designed to run on standard fuel. Using supermarket fuel won't damage your engine or void your warranty.
The "My Mate's Engine" Myth
Correlation isn't causation. Cars develop problems all the time. If someone fills up at Tesco and their car breaks down a week later, they blame the fuel – but the issue was almost certainly unrelated.
Supermarkets sell billions of litres of fuel every year. If their fuel was genuinely damaging engines, we'd see a pattern. We don't.
So What Should You Do?
- Buy the cheapest fuel that meets your car's requirements
- Check your manual – Some cars do require higher octane fuel
- Don't overthink it – Focus on finding the cheapest price, not the "best" brand
The Bottom Line
Supermarket fuel is not inferior. It meets the same standards as branded fuel and is perfectly safe for your engine.
The smartest fuel strategy? Buy the cheapest standard fuel you can find.