Regular Fuel vs. Premium Fuel Myths

By | April 11, 2015

Have you ever heard someone say: You should run 98 in your vehicle because it is better for it? A lot of people swear by running a premium fuel in their vehicle because they’ve been told that it is better, by giving your vehicle a performance boost or better mileage. However I’m here to try and explain to you that it is just a myth. All you’re doing is paying a premium for higher octane petrol, or in other words you’re wasting your money.

First and foremost, you should read your owner’s manual and use what is recommended. If the manual says 91RON you are perfectly fine to run 91RON. Filling up with 98RON is just emptying your wallet faster. It may seem good to buy a higher octane fuel (read premium) and you may think that it is boosting the cars performance, or cleaning the engine, however this is simply not true. Using a higher octane than what is recommended in your owner’s manual will give no benefit what-so-ever.

It is always tempting to believe higher numbers means higher quality. More power and better mileage. This is the perception that gets thrown around with using 98RON (premium). The companies know this and don’t do anything to make you believe otherwise. When we think premium, we think better, right? Wrong.

Whilst premium fuel may burn slower and is more resilient to early detonation, if your vehicle isn’t built or tuned to utilise the higher octane, all that is happening is you’re paying more money for no benefit. Which is just wasting fuel, and your money.

What is an octane rating?
What it boils down to is simply the fuels resistance to detonation. Detonation is affected by numerous things like the timing, octane, compression ratio, and RPMs to name a few. Detonation can be defined as a spontaneous combustion of the remaining air/fuel mixture in the chamber, and octane is how well the fuel can resist this spontaneous combustion.

What is the correct octane for you vehicle?
Read your owner’s manual. It will tell you what is the recommended octane rating for your vehicle. Regular is usually standard for most vehicles, however some sports cars / turbo / supercharged cars need mid-range (95RON) or premium (98RON).

Will higher octane fuel clean your engine better?
No. Higher octane fuel will not surpass regular fuel in preventing, removing, or cleaning deposits in your vehicles engine. All brands of fuel have cleaning detergent additives to help protect the build-up of engine deposits, higher octane fuel does have extra detergent, however for a reason. There will be additional soot caused by certain components in the fuel that aren’t actually combustible. This is where the extra detergent comes into play, to clean off the by-products of the higher octane fuel.

Should I switch to a higher octane?
Open your vehicles user manual, read the section on recommended fuel and use that. If you’ve had your vehicle modified or tuned, then use whatever the tuner / builder recommends for the work that they did. If you’ve built your own engine, you clearly don’t need to be reading this, so use whatever you want.

Can knocking harm my engine?
An occasional knock wont usually do much harm, however if there is persistent knocking, even with a higher octane it will lead to engine damage. If in doubt, get your mechanic to check your vehicle out.