When you pull up at a servo, do you ever find yourself confused by all the different fuels on sale? Surely petrol is petrol, right? Well, not exactly. This guide will help you understand all you need to know about picking the right gasoline.
Tl;DR! I'm at the pump!
Look at the sticker on the inside of your filler cap. Or check your manual for the minimum RON level petrol you can use in your car.
How to understand the various types of petrol on sale in Australia
In Australia, there are several variants of petrol commonly sold at service stations. Each formulation is labelled with a number, which denotes its octane rating or Research Octane Number (RON).
Warning! It's incredibly important that you use the correct petrol to suit your car's engine! It's even more important you don't put diesel in by accident.
Most people mistakenly believe the higher the number, the more powerful or energy-dense the fuel. That's not the case. The number indicates how resistant that particular petrol concoction is to a phenomenon known as engine knock, or in really simple terms, the ability of the engine to govern the timing of when the fuel ignites.
91 RON Unleaded Petrol
91 RON is your basic, standard fuel. It's also the cheapest, non-ethanol containing petrol.
Which cars can I use Unleaded 91 in?
Most petrol cars built after 1986 are compatible with 91 RON unless otherwise stated. If your owner's manual or fuel flap sticker stipulates 91RON, you can use higher octane fuels – though the promises of improved fuel economy and performance may not be appreciable in real-world driving. If you have a car that requires leaded fuel (a classic car for example), you'll need to add a leaded petrol replacement additive or substitute into the tank. You can also have a mechanic retrofit tougher parts to handle the lead-free petrol. You may also decide to use a higher octane fuel for a vintage car.
91 Ron brand names
Regular Unleaded
Unleaded 91
Unleaded Petrol
Special Unleaded 91
95 RON Unleaded Petrol
The first of the "Premium" kinds of petrol, is 95 RON. The increased number of octanes means manufacturers can use different technologies and higher levels of compression to extract optimal efficiency from smaller engines, all without inducing engine knock.
Which cars can I use 95 RON in? Examples of petrol cars that require 95 RON fuel as a minimum include the Volkswagen Polo, Nissan Patrol,Alfa Romeo Stelvio and the Ford Focus. 95 RON is the standard used widely throughout Europe, so that's why you see a lot of imported vehicles use higher octane petrol. Cars that require 91 RON petrol will run happily on 95 and should alter ignition timing to adapt automatically (if they have electronic fuel injection). This could bring slight emissions and economy benefits, though real-world results will vary depending on your car and the conditions you drive in.
95 Ron brand names
Unleaded 95
Caltex Vortex Premium 95
Premium Unleaded 95
Premium 95
Extra 95
98 RON Unleaded Petrol
This fuel is generally a minimum requirement for high-end/performance vehicles, it's also the most expensive petrol.
Which cars can I use 98 RON in?
Typically luxury/high-end/performance petrol cars. For example, the Audi RS5 drinks 98 RON as a minimum.
98 Ron brand names
BP Ultimate Unleaded 98
Supreme+ 98
Shell V-Power Unleaded 98
Unleaded 98
Premium Unleaded 98
Vortex Premium 98 Unleaded
Ethanol E10
Ethanol E10 is just ordinary unleaded petrol (91 RON) with up to 10% ethanol, a type of clear alcohol. Ethanol often is made from the waste products, making it a renewable (depending on the source) and also non-fossil fuel based ingredient. Ethanol contains up to 35% oxygen, which can actually help your engine burn cleaner. While cheaper, E10 contains approximately 3% less energy than unleaded RON 91 petrol.
Which cars can use Ethanol E10?
Check your vehicle's ethanol compatibility online. You shouldn't use E10 in cars that have carburettors (as opposed to fuel injection) and high-performance models.
E10 Ethanol brand names
Caltex Bio E10 Unleaded
E10 Unleaded Petrol
Special E10 94
Shell Unleaded E10
BP Unleaded 91 (with up to 10% renewable ethanol)
E85
E85 has a fuel blend of 70-85% ethanol to 15% petrol. RON measures 105 (this figure varies with the seasons). Availability is quite limited. It is possible to convert existing cars to use E85. It offers better internal engine cooling. V8 Supercars are powered by E85, since the introduction of the fuel in 2009.
Which cars can use Ethanol E85?
Only vehicles specially modified to run on E85 are compatible.
Engine knock
Knocking occurs when the fuel/air mixture within the engine begins to combust before (or in a place other than) it's designed to. This knocking is generally audible, making your engine sound rough, like a bag of spanners and irregular. Knock is sometimes called pinging.
Engine knock will cause damage to internal components. It can cause small pits to form on the surface of precisely machined parts. Because the air/fuel mixture is off, you won't get as complete a combustion, which results in the formation of sooty, carbon deposits. These further compound the problem, resulting in poor running.
It is possible that knocking can lead to a total engine failure, due to the premature breakdown of multiple parts like seals and metal engine components. These bits are exposed to the overheating and stresses outside of the engine's design specifications, caused by the pressures of knocking.
This video from spark plug manufacturer NGK demonstrates the regular combustion process and knocking. Engine knock starts at 0:59.
Average NSW petrol prices December 2019
Fuel
Average Price in NSW
Unleaded 91
201.4 cents
Ethanol 94 (E10)
200.6 cents
Premium 95
217.5 cents
Premium 98
224.4 cents
*Figures from NSW Fuel Check
Frequently asked questions about petrol types
Can I use a higher RON fuel than recommended?
Yes, you can put a higher RON fuel into your car, for example, 98RON into a 91RON minimum car. You may or may not experience better efficiency from your engine. Fuel producers list possible benefits of higher octane fuels as:
Better engine responsiveness
Higher engine efficiency
Fuel economy gains
Emission improvements
I've accidentally put a lower octane fuel in. What should I do?
If you put 91RON petrol into a high-performance car that is designed for 98RON premium fuel, you should read your owner's manual or contact the manufacturer first before starting the engine. Newer cars will likely auto adjust ignition timing thanks to a knock sensor and you may be ok to run the car, topping up with premium fuel to compensate. However, you do run the risk of possibly damaging internal components. Engineers from major car companies say it's risky, so it's best to pay attention at the pumps and follow the guidance on your fuel cap sticker, rather than make a mistake. Older cars can't re-tune on-the-fly.If you decide to use the car, listen out for new and unusual pinging noises, like metallic pops. If you hear this, the engine is suffering from knocking. If you're really worried, there are fuel additives on sale that can boost fuel octane levels.
Help! I've put the wrong fuel in my car! What do I do now?
If you put diesel into a petrol vehicle or vice versa, do not start the engine! You'll need to contact a misfuelling service. They'll have to drain the fuel tank and flush your fuel lines to prevent catastrophic (and costly) damage.
Can I use E10 Ethanol?
First, you need to check whether your car is compatible with Ethanol fuel. The Federal Chamber of Automotive Industries (FCAI) has a guide on whether your car can run Ethanol blend unleaded petrol.
Ben Gribbin is an automotive writer at Finder. He is a life-long car enthusiast, bringing many years of experience working with and writing about cars. During his time, Ben has been a freelance writer, editor and reviewer for a number of leading publications across the UK. He was voted the Guild of Motoring Writers Breakthrough Blogger in 2015.
Thinking about buying a car to get to uni? Find out everything you need to know about buying a car as a student, including where to look for one and how to get finance.
How likely would you be to recommend finder to a friend or colleague?
0
1
2
3
4
5
6
7
8
9
10
Very UnlikelyExtremely Likely
Required
Thank you for your feedback.
Our goal is to create the best possible product, and your thoughts, ideas and suggestions play a major role in helping us identify opportunities to improve.
Important information about this website
finder.com.au is one of Australia's leading comparison websites. We are committed to our readers and stands by our editorial principles
We try to take an open and transparent approach and provide a broad-based comparison service. However, you should be aware that while we are an independently owned service, our comparison service does not include all providers or all products available in the market.
Some product issuers may provide products or offer services through multiple brands, associated companies or different labeling arrangements. This can make it difficult for consumers to compare alternatives or identify the companies behind the products. However, we aim to provide information to enable consumers to understand these issues.
We make money by featuring products on our site. Compensation received from the providers featured on our site can influence which products we write about as well as where and how products appear on our page, but the order or placement of these products does not influence our assessment or opinions of them, nor is it an endorsement or recommendation for them.
Products marked as 'Top Pick', 'Promoted' or 'Advertisement' are prominently displayed either as a result of a commercial advertising arrangement or to highlight a particular product, provider or feature. Finder may receive remuneration from the Provider if you click on the related link, purchase or enquire about the product. Finder's decision to show a 'promoted' product is neither a recommendation that the product is appropriate for you nor an indication that the product is the best in its category. We encourage you to use the tools and information we provide to compare your options.
Where our site links to particular products or displays 'Go to site' buttons, we may receive a commission, referral fee or payment when you click on those buttons or apply for a product. You can learn more about how we make money.
When products are grouped in a table or list, the order in which they are initially sorted may be influenced by a range of factors including price, fees and discounts; commercial partnerships; product features; and brand popularity. We provide tools so you can sort and filter these lists to highlight features that matter to you.
Please read our website terms of use and privacy policy for more information about our services and our approach to privacy.
