Fuel Types
Premium vs Regular Petrol (2026)
Premium vs regular petrol explained for Australia: what 91, 95 and 98 RON mean, when premium is required, and when it is wasted money.
Key points
Key takeaways
91, 95 and 98 are octane ratings, not quality scores.
Premium fuel only pays off when your engine requires or can genuinely use the higher octane.
A 10-15c/L premium price gap can add hundreds of dollars a year for no benefit in a car designed for 91.
The safest rule is to follow the minimum RON on the fuel flap or owner manual, then find that grade cheaply.
Using this guide
Before you act on the guide
Check the station price, report time and distance before changing your route.
Quick answer: should you buy premium?
Buy premium petrol only when your car specifies 95 or 98 RON as the minimum fuel, or when the manufacturer recommends it for a clear performance or towing use case you actually need. If your car is designed for regular unleaded 91, paying extra for 95 or 98 usually does not give you more useful power, better economy or a lower running cost.
What 91, 95 and 98 mean
The numbers are Research Octane Number ratings. Octane measures how resistant the petrol is to knocking under compression. It is not a measure of how much energy is in each litre. A higher number helps engines with high compression, turbocharging or performance tuning. It does not turn a regular engine into a cheaper-to-run one.
Regular, premium and E10 compared
| Grade | Typical use | Decision rule |
|---|---|---|
| U91 | Mainstream petrol cars that specify 91 minimum | Usually the sensible default when E10 is not suitable. |
| E10 | Approved petrol cars that can use an ethanol blend | Compare the E10 discount with U91 and check compatibility first. |
| P95 | Cars that specify 95 minimum or recommend premium | Use it when the manual requires it; otherwise compare the cost carefully. |
| P98 | High-compression, turbo and performance engines that specify 98 | Worth paying for when the engine is designed around it. |
When premium is worth it
Premium petrol is worth paying for when the manufacturer lists 95 or 98 as the minimum fuel. In that case, cheaper 91 can force the engine to pull timing, lose power and use more fuel. Premium can also make sense for some engines under sustained load, such as towing, if the manual recommends it.
When premium is wasted
If the fuel flap or manual says 91 minimum, the engine has been designed to run safely on regular unleaded. In that situation, higher octane usually cannot deliver enough economy improvement to cancel the price gap. On a 55-litre fill, an extra 12c/L for P98 costs $6.60 every fill. Over weekly fills, that is more than $340 a year before any benefit is proven.
How to check your car
Start with the fuel flap, then the owner manual, then the manufacturer specification for your exact model and year. Watch the wording. "Minimum 95" means do not go below 95. "91 minimum, 95 recommended" means 91 is safe and premium is optional. "Premium only" means the higher grade is part of the engine requirement.
Use the right grade, then compare the price
The saving comes from buying the correct fuel at the lowest useful station, not from buying the most expensive grade by habit. Once you know the grade your vehicle needs, open the map, filter by that fuel and compare station prices, update times and distance before filling.
Common questions
Frequently asked questions
It is better only for engines designed to use the higher octane. For cars that specify 91 minimum, 98 is usually an expensive habit rather than a useful saving.