Adelaide Unleaded Slips Under $2 at Blair Athol as South Australian Diesel Climbs
According to pricing data collected at 8:13am AEST on 10th Sep 2026, unleaded at Blair Athol in Adelaide averages 197.8 cents per litre across five stations, down 7.1 cents on the previous reading and back under the $2 mark. Diesel across South Australia has gone the other way, up 1.3 cents to a state average of 260.2 cents across 372 stations.
Petrol and diesel usually drift in loose formation, because they share the same refined product costs and the same freight lines out of the terminals. When they separate this clearly it is generally the retail cycle doing the work rather than anything happening at the wholesale end.
Blair Athol leads the Adelaide discount round
Unleaded is not the only fuel easing there. Premium 98 in the same suburb has come down 11.3 cents to 220.6, the largest movement recorded anywhere in the country this round. Two fuels at one location falling together, and by that margin, points to a discount phase rather than a single servo promotion.
For drivers on the northern side of Adelaide the sum is simple. A 7.1 cent saving is about $4.26 on a 60 litre fill. Anyone running higher octane is closer to $6.80 a tank against a week ago. Adelaide discount windows tend to run for a matter of days rather than weeks, so the timing counts as much as the location. Our guide to the best time to fill up covers how the Adelaide cycle usually behaves.
Further south, Mount Gambier is doing something similar in the premium grades, with 98 down 7.0 cents to 224.8 across six stations. That is worth noting for a regional centre, which normally trails the capital by several days when a discount round rolls through.
The diesel picture is a different story
South Australian diesel now carries the highest state average in the country outside the Northern Territory, sitting at 260.2 cents. The spread inside that average is very wide. The cheapest diesel recorded in the state is 234.9 and the dearest 350.0, a gap of 115.1 cents.
Hawker sits near the top of that range. Diesel there has lifted 6.8 cents to average 280.9 across five stations, roughly 20 cents above the state average and around 46 cents above the cheapest sites in the state. Freight distance explains most of that, though not all of it. Closer to the Murray, Barmera averages 247.0 and Tintinara 246.9, both well under the state figure, so distance is not the whole answer.
Diesel demand from agriculture and transport holds firm regardless of the retail cycle, which is why diesel rarely gets pulled down when petrol enters a discount phase. That has been the pattern right through winter.
Queensland offers a useful comparison
Across the border the two fuels are moving together. In Queensland, Roma records unleaded at 202.5 cents, down 8.4 cents, with diesel in the same suburb down 8.9 cents to 255.0. That is the opposite of the South Australian split.
Charlton has posted the largest diesel decrease in the country at 11.3 cents, taking the average to 251.6 across five stations, while Ingham is down 7.9 cents to 258.0. On the coast, Labrador still holds the cheapest metro unleaded in the sample at 203.0, with E10 prices there marginally lower again at 202.3.
Queensland regional centres often reset their pricing on a slower rhythm than the capital cities, so a decrease that arrives late can land in the same week that Adelaide begins its own discount round.
What this means at the bowser
In Adelaide the move is to fill while the window is open. Current unleaded petrol prices show the gap between the cheapest and dearest Adelaide sites is still wide enough that a short detour pays for itself.
Diesel drivers face a different calculation. With the state average climbing and the spread stretching past 115 cents, the saving comes from knowing which sites hold the lower prices rather than waiting for a cycle that may not arrive.
Location and timing remain the two levers that matter in fuel savings. In South Australia this week petrol drivers have timing on their side, and diesel drivers have only location.
