For two decades, Australia sold some of the dirtiest petrol in the developed world. Regular 91 was allowed 150 parts per million of sulfur, fifteen times the European limit, and premium 50 ppm. That changed on 15 December 2025, was partly reversed three months later during the Middle East supply crisis, and is due to snap back for good on 1 January 2027. If you own a car built to Euro 6d rules, or a diesel with a particulate filter, the timeline matters.
What the standard covers
The Fuel Quality Standards Act 2000 and the determinations made under it set the legal specification for every fuel sold in Australia. For petrol that means minimum octane (91/81 RON/MON for regular, 95/85 for premium; 98 is sold against the premium standard), and maximum sulfur, aromatics, benzene, olefins, lead, phosphorus and a long list of other parameters. Diesel, biodiesel, E85 and autogas each have their own determination. The standards are national; states can add to them but not weaken them. Compliance is policed by the Department of Climate Change, Energy, the Environment and Water and the National Measurement Institute through unannounced sampling.
The December 2025 upgrade
From 15 December 2025 two changes took effect:
- Sulfur capped at 10 ppm in all petrol grades, down from 150 ppm for 91 and 50 ppm for 95 and 98. This brought Australia into line with Europe, the US, Canada, China, India and New Zealand. Sulfur poisons catalytic converters and oxygen sensors over time and produces sulfur dioxide when burnt.
- Aromatics capped at 35 per cent in 95 RON petrol, down from 45 per cent. Aromatics are octane-boosting hydrocarbons that occur naturally in crude; at high levels they increase particulate emissions and can cause operability problems in engines fitted with petrol particulate filters. The 91 and 98 grades kept the 45 per cent cap.
Both changes exist to support Euro 6d emission rules, which apply to new light-vehicle models introduced from December 2025 and to all new light vehicles by 2028. Euro 6d engines, with their particulate filters and close-coupled catalysts, are designed around ultra-low-sulfur fuel. The government's own estimate of the cost was small: under a cent a litre for the sulfur change across all grades, plus about 0.9 cents a litre for the aromatics change on 95, which it put at roughly $22 a year for a 95-RON car driving 15,000 km.
Diesel was unaffected because Australian diesel has been capped at 10 ppm sulfur since 2009.
The 2026 relaxation
On 28 February 2026 the conflict between the United States, Israel and Iran escalated and the Strait of Hormuz, through which about a fifth of the world's oil moves, was effectively closed. Refined fuel prices spiked worldwide and Australia, which imports most of its petrol and diesel from Asian refineries, faced supply pressure.
On 12 March the government temporarily amended the petrol standard to allow up to 50 ppm sulfur in all grades. The logic was that petrol produced in Australia and the region that met the old 50 ppm specification but not the new 10 ppm one was being exported; allowing it back into the domestic pool added an estimated 100 million litres a month, or roughly two days of national consumption. The measure was initially set to run for 60 days, then on 1 April was extended. The timeline that now applies:
- Up to 50 ppm sulfur in all petrol grades until 30 September 2026.
- Up to 40 ppm during a three-month transitional period to 31 December 2026, so suppliers can clear stock.
- Back to 10 ppm in all grades from 1 January 2027.
Diesel was also temporarily allowed a flash point of 60.5°C rather than 61.5°C, a safety-in-handling specification with no effect on how the fuel burns, until 30 September 2026.
Worth keeping in perspective: 50 ppm is what premium unleaded was allowed right up until December 2025, and a third of what 91 was allowed. Petrol during the relaxation is dirtier than it was in January 2026, but cleaner than it was for all of 2025 and every year before.
What it means for your car
Cars sold before December 2025. Nothing changes that you will notice. Your car was designed for, and has spent its life on, fuel with more sulfur than the relaxed limit allows. Catalyst sulfur poisoning is cumulative and gradual, and a few months at 50 ppm after years at 150 ppm is not going to register.
Euro 6d cars introduced since December 2025. These are the vehicles with a legitimate concern. Their emission systems assume 10 ppm fuel. Short-term exposure to 50 ppm is unlikely to cause damage, but it can increase the rate at which the petrol particulate filter and oxygen sensors foul, and it can raise tailpipe emissions during the period. Drivers of new cars that specify 98, particularly those fitted with a particulate filter, should keep using the grade the manufacturer requires and treat the relaxation as a reason not to skimp. Once the 10 ppm limit returns, the cumulative effect of a few months on 50 ppm fuel should be minor.
Diesels. No change to diesel sulfur at any point. The flash-point tweak is irrelevant to engine operation.
Why this took so long
Australia's fuel standards review began in 2018 and produced a range of options, from harmonising fully with Europe (which would have meant abolishing 91) to simply cutting sulfur. The cost-benefit analysis found that phasing out 91 had a net cost to the community because so much of the fleet depends on it, so the chosen path kept 91 and cut its sulfur. The 10 ppm date was originally 2027, was brought forward to December 2024 after the 2022 election, and was then pushed back to December 2025 to align with the Euro 6d timetable and to avoid straining supply. It arrived with three months to spare before a war tested it.
Where to check the current rule
DCCEEW maintains the authoritative page on the regulation of Australian fuel quality, including the current temporary determinations and their end dates, and any new section 13 variations granted to individual suppliers. If a supplier is granted a variation, it must still label the fuel.
FAQs
Is Australian petrol currently 10 ppm sulfur?
Not necessarily. Until 30 September 2026 any petrol grade may contain up to 50 ppm, and up to 40 ppm until 31 December 2026. From 1 January 2027 the 10 ppm limit applies to all grades again.
Should I switch from 91 to premium to avoid the higher sulfur?
No. The relaxation applies equally to 91, 95 and 98, so premium is not cleaner during this period. Use the grade your car specifies.
Did the December 2025 change make fuel more expensive?
The government's estimate was under a cent a litre for sulfur and about 0.9 cents a litre for the 95-RON aromatics cap, an amount swamped by ordinary price cycles and by the 2026 crisis.
Is 95 still limited to 35 per cent aromatics during the relaxation?
Yes. The temporary change was to sulfur only.
What happens if a servo sells fuel outside the standard?
Suppliers face penalties under the Fuel Quality Standards Act, and DCCEEW can investigate consumer reports. Compensation for vehicle damage is a matter for state consumer affairs regulators and your insurer, not the department.