NSW Diesel Averages 257 Cents but Oberon and Bomaderry Sit 20 Cents Under It
At 2:04pm AEST on 9th Sep 2026, the diesel average across 1,249 New South Wales servos read 257.0 cents a litre, up 3.2 cents on yesterday. That was the largest daily movement of any Australian state today. Victoria lifted 1.0, Queensland lifted 0.6, and Tasmania barely moved at all.
So NSW diesel went up. That is the headline, and it is close to useless for anyone deciding where to fill this afternoon.
Where a fuel average comes from
The same NSW data set that produced 257.0 cents also contains a cheapest board of 219.5 and a dearest of 336.0, a spread of 116.5 cents between the two ends of one state on one afternoon. Think of it this way. If I told you the average height at a high school is 165 centimetres, you would learn almost nothing about the Year 7 student standing next to the basketball captain. The average is real, but nobody is actually that number.
Fuel averages work the same way. You get 257.0 by adding a boutique highway stop charging north of 300 to a discount volume site charging 220, then dividing. No motorist ever pays 257.0. What matters is which side of that number your regular servo sits on.
Where the NSW numbers actually land
Here is what the cheapest NSW diesel suburbs look like right now, and notice how many of them are nowhere near Sydney.
- Oberon, four sites, averaging 242.4 with the cheapest at 237.9
- Bomaderry, four sites, averaging 243.4 with the cheapest at 233.9
- Mayfield, four sites, averaging 243.2 with the cheapest at 238.5
- Granville, three sites, averaging 244.8
- Wauchope, five sites, averaging 245.6
- Gunnedah, four sites, averaging 246.6
- Cessnock, three sites, averaging 246.8
Every one of those suburbs is at least ten cents under the state average, and Bomaderry's cheapest board is more than 23 cents under it. On a 70 litre ute tank, 23 cents a litre works out to about 16 dollars, which is worth a few minutes of looking.
Why the cheap suburbs are scattered rather than clustered
You might be wondering why a Blue Mountains town like Oberon and a Newcastle industrial suburb like Mayfield land in the same price band when they have nothing else in common. It has little to do with distance from a refinery. What counts is how many diesel customers a site expects to see and how closely those customers watch the board.
Mayfield and Granville sit in heavy freight corridors. Trucks buy diesel in 200 litre lots and they shop hard, so retailers there compete on cents rather than convenience. Oberon has timber and haulage traffic doing the same thing on a smaller scale. A highway site serving tourists who fill once and never come back has no reason to sharpen a price, because the customer is not comparing anyway. Coastal Yamba shows the pattern from the other direction, with four sites all within 1.6 cents of each other at about 245.8. When nobody is fighting for repeat trade, prices settle together rather than falling.
That is also why NSW carries a 116 cent spread while Tasmania, with only nine reporting diesel sites, spans just 13 cents. More competitors does not automatically mean a lower average. It means a wider range, and a wider range is where the saving sits.
What today's 3.2 cent lift actually means
A statewide lift of that size usually reflects wholesale costs working their way through the network rather than any single retailer making a decision. A wholesale move reaches everyone, but retailers pass it on at different speeds. The sites that were already sharp tend to absorb part of the increase to protect their volume, while the sites that were already expensive pass it straight on. The gap widens.
Practically, that means a day like today is the wrong day to fill at your nearest servo out of habit. Check the current diesel prices near you, compare a few sites, and if you want to see how far this week sits from the last one, the price trends page tracks the movement over time.
The average will go on telling you 257.0. Oberon and Bomaderry are the numbers worth acting on.
