Ever pulled into one of the many UK petrol stations and wondered what the difference is between unleaded and super-unleaded petrol? With a greater amount of choice available nowadays, it can sometimes be difficult to get your head around the different options. Gone are the days when it was just petrol and diesel to choose from at the pump.
Luckily, to help you better understand what juice you should be putting in your tank, we've put together a simple guide to help you on your way.
Definition
Super-unleaded petrol is basically a higher-octane version of unleaded regular petrol. Along with its high-performance diesel counterpart, super-unleaded petrol is one of the premium fuels.
How does super-unleaded compare with unleaded regular petrol? Well, super-unleaded has a higher-octane fuel rating and can improve performance on certain cars. It's designed to be more fuel-efficient with a smoother engine operation, whilst also containing additives designed to keep your engine clean, so there's a good chance that super-unleaded will make your car perform better for longer. You might also benefit from more power, improved acceleration, better pulling power at low revs and a smoother and quieter drive when on the move.
OK, But What is High-Octane Fuel?
High-performance engines typically compress their fuel more. The higher the octane fuel level, the more likely it is that you'll be able to avoid unexpected explosions which might damage your engine.
Standard fuel typically has a 91-95 octane rating, whilst premium or 'super' fuel boasts a higher rating of around 98-99.
What Octane is Super-Unleaded?
Super-unleaded fuel usually has an octane rating of between 97 and 99.
That's a fair bit higher than ordinary unleaded petrol, which usually has an octane rating of around 91.
Is Super-Unleaded Better for your Car?
If you drive a prestige or high-performance car, then yes, definitely. The manufacturer might even recommend that you use a premium fuel (such as super-unleaded) to help improve overall driving performance and fuel efficiency.
If, however, you drive a car with a low-powered engine and mostly use it for small local errands, then you’re unlikely to see much benefit from using a premium fuel like super-unleaded. Unfortunately, a family hatchback isn't going to start feeling like a supercar just because you've put super-unleaded in it.
If you’re used to using regular unleaded petrol, it might be worth trying out premium unleaded fuel in the tank at least once in order to see if there are any noticeable differences. That way you can better notice any improvements to your current car and, if so, whether they outweigh the extra financial cost that comes with using super-unleaded.
How Much Does Super-Unleaded Cost?
Speaking of the extra cost, it's obviously more expensive, but by how much?
As of 14 June 2022, standard unleaded petrol costed around 175p per litre whilst super-unleaded petrol costed around 181.9p per litre.
In other words, that's a price difference of around just 7p.
Can You Mix Unleaded Petrol and Super-Unleaded Petrol?
Certainly can. It's safe both for you and your car.
However, the RAC does still suggest sticking to the recommended octane number for your vehicle.
What About Supermarket Fuel?
There's no major difference between supermarket fuel and branded fuels. Pretty much all petrol engines and diesel engines are designed to work with supermarket fuel.
What's the Best Petrol for My Car?
Most cars are designed with an optimum fuel type in mind. You can find out what that is by looking at the info displayed near your fuel cap or in the owner's handbook.
As a general rule, it's fine to use a higher-octane fuel than is recommended for your car (though depending on your specific car, there might not be any advantage in doing so), but using a lower-octane fuel than is recommended could cause engine damage.
What If You Put the Wrong Fuel In?
You won't get this problem with unleaded and super-unleaded (because, as we say, they're compatible), but just while we're on the topic, here's what to do if you put diesel in a petrol car, or vice versa.
Don't put the key in the ignition; leave your engine switched off
Let a staff member know
Put the gearstick in neutral
Push the car to a safe place
Call breakdown cover or RAC Fuel Patrol to drain and flush the car's fuel system
Call your insurance provider as soon as possible
Moral of the story, amigos: choose your fuel wisely!
FAQs
Is it OK to put super-unleaded in an unleaded car?
Yes, it's perfectly OK, even if it might not always lead to better performance (depending on the car).
What is the benefit of super-unleaded?
The higher-octane rating of super unleaded means that it delivers higher performance, having a positive impact on power, performance and fuel efficiency.
Is super-unleaded E5 or E10?
Super-unleaded petrol falls into the E5 category.
Is super-unleaded better for your engine?
Only if you have a high-performance engine.
What happens if you mix super-unleaded and unleaded?
Nothing bad. You'll just end up with a mixed-grade petrol of around 96 RON.