WA Alleges a Servo Chain Sold 91 as Premium 98. The Gap Is 25 Cents

You can check the price on the board before you pull in. You can check the litres on the bowser and the total on your receipt. What you can't check is whether the petrol going into your tank is the grade you paid for, and that's the question behind a court case lodged in Perth this week.

What the regulator says happened

On 9 November, Western Australia's Commissioner for Consumer Protection, Trish Blake, announced civil proceedings in the Supreme Court of WA against Burk Fuel Pty Ltd, Burk Pty Ltd and the companies' sole director. The Commissioner alleges they made false or misleading representations about the octane rating of fuel, in breach of the Australian Consumer Law.

The claim is easy to state. According to the Commissioner, motorists paid for fuel sold as Premium 95 and Premium 98, and independent testing in late 2025 and early 2026 indicated the product was consistent with regular unleaded 91. The alleged conduct covers multiple WA sites between 1 July 2025 and 2 February 2026. Burk is reported to run 14 servos across Perth and regional WA, along with a few in Victoria.

Investigators executed search warrants at metropolitan and regional service stations, with help from the federal Department of Climate Change, Energy, the Environment and Water. Court documents, first reported by WAtoday and summarised by the trade publication ServoPro, allege the chain sold more than 7 million litres of Premium 98 over the period while buying 1.69 million litres of it.

None of this has been tested in court. Burk has denied the allegations since the investigation became public in April. It says it buys from a reputable supplier, checks its fuel regularly and will defend the case. If the claim is proven, the Commissioner is reported to be seeking financial penalties, refunds for customers, a five year ban on selling fuel in WA and a disqualification from managing corporations.

"When motorists choose to pay more for premium fuel, they should be able to rely on the information provided by the retailer and have confidence they are receiving the product they purchased," Ms Blake said.

Why octane is worth arguing about

Here's what's really going on underneath a case like this. Premium is where the money is.

The ACCC's petrol report for the December quarter of 2025 put premium 98 at an average 204.6 cents a litre across the five largest cities, against 180.4 for regular unleaded. That's a 24.2 cent gap. Premium 95 sat 16.6 cents above regular. The same report said sales of 98 had reached their highest quarterly level in data going back to 2016, and it repeated an earlier ACCC finding that premium grades are significantly more profitable than other petrol.

The gap is much the same today. Petrolmate's analysis of official FuelWatch prices on 14 November found 718 WA servos listing both grades, with a median gap of 25 cents a litre between regular unleaded and premium 98. For premium 95 the median gap was 17 cents across 523 sites.

To put this in perspective, a 50 litre fill of 98 costs about $12.50 more than the same fill of 91. Do that weekly and it's $650 a year, spent on a quality you can't see, smell or measure. As Ms Blake told ABC Radio Perth, "You have to be able to rely and trust on the trader."

So who actually tests the stuff?

Fuel quality is a federal matter under the Fuel Quality Standards Act 2000, and the sampling is done by inspectors from the National Measurement Institute. In the year to June 2023, the latest detailed breakdown we could find, those inspectors completed 684 fuel quality audits and sent 712 samples to the lab. Twelve failed, or 1.7 per cent. Most of the failures involved diesel flash point or petrol chemistry. One was a premium 95 sample that came in under its octane minimum.

Nearly everything tested was what it claimed to be, which is reassuring. Ms Blake has also said samples taken from other WA traders during this investigation matched what was advertised. But 712 samples a year is a thin net over a country with thousands of servos. That may be why the WA claim, as reported, sets fuel purchases against fuel sales grade by grade, alongside the lab results.

There's a reason nobody checks octane at the kerb. The number on the bowser is defined by a single cylinder test engine that the Waukesha Motor Company of Wisconsin designed and built in 45 days, starting in December 1928. Labs still rate petrol on descendants of that engine today. They run the fuel, measure the knock and compare it with reference blends. You can't do that with a dipstick and a jar.

Australia has been here before

Going back a couple of decades, there are two episodes worth knowing about.

In early 2000, operators were caught blending toluene into petrol. Toluene is an industrial solvent that carried no excise, at a time when petrol excise was about 44 cents a litre. A handful of Sydney servos were publicly named, Canberra put an excise equivalent duty on the solvents that March, and the Fuel Quality Standards Act followed in December of the same year.

Then in December 2007 the Federal Court fined a northern NSW distributor, trading as Ballina Petroleum Distributors, $400,000 and its managing director $70,000 after an ACCC prosecution. They had admitted diluting about two million litres of fuel sold as lead replacement and premium grades with regular unleaded between September 2004 and June 2007. The judge observed that customers were vulnerable because all they had to go on was the label on the bowser. Nothing about that has changed.

The penalties have. Federal Parliament this year doubled the maximum for false or misleading conduct under the consumer law to $100 million, a change the Treasurer pitched as putting petrol companies on notice. Which ceiling applies to conduct alleged to date from 2025 is a matter for the court.

What 91 does in an engine built for 98

Octane measures how well a fuel resists knock, which is fuel igniting too early under compression. Engines tuned for 95 or 98 squeeze the mixture harder and need that resistance. Modern cars carry knock sensors that wind back the ignition timing when they detect it, so one tank of the wrong grade is unlikely to wreck anything. You pay in other ways, with less power and more fuel used, and prolonged heavy knock can cause real damage.

In other words, a driver sold the wrong grade could be paying more per litre and burning more litres as well.

The practical upshot

The case has a long way to run, and Burk gets its day in court like anyone else. Until then, the label on the bowser is the only evidence most of us ever see. Keep an eye on this space.