Can my car use E10?
Check E10 compatibility and octane for your car, boat or small engine, and the discount E10 needs against U91.
95 vs 98 petrol: premium vs regular explained (2026)
Premium vs regular fuel explained for Australia: what 91, 95 and 98 RON mean, 95 vs 98, premium diesel, and when premium is wasted money.
By the FuelRadar team4 min read
Quick answer: should you buy premium?
95 and 98 are both premium unleaded; 98 has the higher octane rating (98 RON against 95 RON). Buy premium petrol only when your car specifies 95 or 98 RON as the minimum fuel, or when the manufacturer recommends it for towing or performance 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.
95 vs 98 petrol: what is the difference?
Both are premium unleaded; 98 has a higher octane rating (98 RON) than 95 (95 RON). The NSW Government says a premium fuel must be at least RON 95, and the Australian Government fuel-quality page says 98 RON petrol must meet the 95 RON standard. Use 98 when the fuel flap or owner manual says 98 minimum. If it says 95 minimum, 95 meets the requirement and 98 is an optional extra cost. If it says 91 minimum, either premium grade is optional.
Is 98 RON the same as 98 octane in the US?
No. Australia labels petrol by Research Octane Number (RON). Pumps in the United States and Canada show the average of RON and the Motor Octane Number, which is typically 4 to 6 numbers lower. So a US car manual asking for 91 octane is not asking for Australian 91 RON; check the manual for a RON figure, or ask the manufacturer's Australian arm which grade to use.
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 | When to use it |
|---|---|---|
| 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. NSW Government guidance says drivers should use petrol with an octane rating at least equal to the manufacturer's specification. 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.
Premium diesel vs regular diesel
Premium diesel is a brand's diesel with an extra additive package. Ampol, for example, says its Amplify Premium Diesel additive includes a detergent to keep fuel injectors clean, a corrosion inhibitor, a friction modifier and a foam inhibitor. Premium diesel is not a higher grade in the way 98 is above 91: RAC WA says premium diesels have the same cetane number as regular diesel and recommends regular diesel. Follow the owner manual; if it does not ask for a premium diesel, compare the regular diesel price first and treat the premium as optional.
Sources and limits
The NSW Government E10 facts explains that RON measures resistance to premature ignition and tells drivers to meet the manufacturer's minimum octane rating. The Australian Government fuel-quality page describes national petrol standards for 91 and 95 RON and says 98 RON must meet the 95 RON standard. These standards describe fuel quality; the vehicle manual remains the source for grade compatibility.
The ACCC petrol price-cycle guidance says regular-unleaded buying tips may also apply to P95, P98 and E10 because the main unleaded grades often move similarly. It limits those tips to the five largest cities and does not apply them to diesel, LPG or most regional locations. The RON and US octane comparison is from the Wikipedia octane rating article, and the premium diesel notes are from Ampol's additive page and RAC WA's fuel myths article. Sources checked 26 August 2026; the 95 vs 98, US octane and premium diesel sections were added on 27 October 2026.
Common questions
Is 98 petrol better than 91?
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.
Can I use 91 if my car says premium recommended?
If the manual says 91 minimum and premium recommended, 91 is generally safe. If it says 95 or 98 minimum, use that minimum grade.
What is the difference between 95 and 98 petrol?
Both are premium unleaded; 98 has the higher octane rating. Use 98 when your car specifies 98 minimum. If it specifies 95, 95 meets the requirement and 98 is an optional extra cost.
Is premium diesel better than regular diesel?
Premium diesel adds a brand additive package, such as detergents to keep injectors clean. RAC WA says premium diesels have the same cetane number as regular diesel and recommends regular diesel. Follow the owner manual.
Does premium petrol clean the engine?
Some premium fuels include stronger detergent packages, but that does not make every premium fill financially worthwhile. Use the grade your car requires and compare the pump price.
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