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All our stores in Sydney are “Covid safe registered” and open for business, Please call 1300 266 844 to book an appointment

Discover Mechanical

Does the Type of Fuel you use Matter?

Person looking unsure at the fuel pump, wondering what petrol to use.
With so many types of fuel at the petrol station, are you unsure which one you should really be using? Or with the rising cost of fuel, do you find yourself wondering if your car really benefits from premium fuel, when you could save a few dollars instead?
Here, we’ll take a look at the different types of fuel that you’ll find at the petrol station, and what type of fuel you’re best to use in your vehicle.
Hand on fuel pump that’s inserted into a car’s fuel tank.

Unleaded Petrol

When it comes to unleaded petrol, it’s not as simple as one choice. In fact, there are several types of unleaded petrol, 91, 95 and 98. These all have a different octane rating known as a RON (Research Octane Number).
The octane rating is an index that indicates the fuel’s resistance to burning too early inside the engine, otherwise known as ‘knocking’. The higher the RON, the more resistance the fuel has to pre-ignition. This makes the vehicle run with greater efficiency.

RON 91

Known as regular unleaded, this is the lowest octane level unleaded fuel available in Australia. Typically, this is the cheapest unleaded fuel.

RON 95

Known as premium unleaded, this is the lowest octane level premium fuel. As a result, it typically costs a little more than regular unleaded, but is cheaper than premium unleaded. In other words, when it comes to unleaded petrol, it’s usually known as middle of the road cost wise.

RON 98

Also known as premium unleaded, with a RON of 98 it has the highest octane rating of the two premium unleaded fuels. This typically makes it more expensive than 91 and 95 unleaded fuel.
Man holding a petrol pump in his hand, looking up to the sky with an exasperated expression.

Which Unleaded Petrol Should You Use?

While you may think it doesn’t matter all that much, choosing the right unleaded fuel for your vehicle can make a difference, both financially and performance wise. Vehicle manufacturers design engines for a minimum octane rating. To find out what octane your engine was designed for, you can take a look in your owner’s manual.
If it’s recommended that your vehicle use regular unleaded (91), you can still use premium 95 or 98 unleaded fuel, without causing harm to your engine. However, it may negatively impact how much you’re spending on fuel. Opting for a higher RON than what your vehicle manufacturer recommends is unlikely to result in better vehicle performance or fuel efficiency. It will, however, cost you more.
If your vehicle manufacturer recommends a higher octane fuel, such as premium unleaded 98, then it isn’t recommended that you use a lower octane fuel. This can lead to reduced fuel economy and performance.


Made from crops, including sugarcane and corn, there are currently two ethanol blend fuel varieties available in Australia. These are:


E10 is a 10% ethanol blend, mixed with 90% unleaded fuel. When compared to regular unleaded fuel with a RON of 91, E10 has a slightly higher octane of 94. What does this mean? Well, if you opt for E10 over regular unleaded petrol, you may notice a slight increase in engine performance.
The drawback? Ethanol decreases the energy level of the blend, which can reduce your vehicle’s fuel efficiency. That being said, you will often find that E10 is slightly cheaper than regular unleaded (91), which may mean the decrease in fuel efficiency is not such an issue when it comes to fuel costs.


E85 fuel is a blend of anywhere between 50 and 85% ethanol with unleaded fuel, with an octane level of 100. Just as with E10, E85 has a lower energy density than regular unleaded fuel that can negatively impact on fuel efficiency.
Often considered a racing fuel for high performance cars due to its performance capabilities, there are very few vehicles designed to run on E85. As with E10, always refer to your vehicle manufacturer's fuel recommendations.
The use of E85 in an incompatible engine can cause damage to the fuel lines and other components, and may even result in the vehicle not starting at all.

What Vehicles Can Use E10?

If your vehicle was manufactured in 2005 or onwards, E10 is usually acceptable as a substitute for regular unleaded (91). Always check with your car manufacturer’s recommendations first. Using E10 in a vehicle not built for it can result in catastrophic failure of the fuel system as ethanol can cause corrosion and damage to fuel lines and fuel pumps, if not designed for use with E10.


Diesel powered vehicles can offer greater fuel efficiency than petrol engines when ideal driving conditions are met. If you own a diesel vehicle, then clearly your choice of fuel is very clear - diesel fuel.
Understanding the different types of fuel available, and more importantly, which type of fuel your vehicle requires is essential to both vehicle upkeep and performance. The fuel your vehicle manufacturer recommends is specific to the design of the engine and its requirements.
Fuel pumps
Using the right fuel not only prevents potential damage to your engine, it ensures that your vehicle is performing as intended. If your vehicle is using the correct fuel, and you maintain regular vehicle servicing, then it stands to reason that you are most likely to experience the best fuel efficiency possible for the type of vehicle you drive, your driving style and typical driving conditions.
BestDrive. You drive, we care.

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