Don't get pumped.
As of 9 September 2026, the cheapest Premium Diesel in Western Australia is 232.7c per litre at Costco, Casuarina — versus the Western Australia average of 257.7c (1.0c below the national average of 258.7c). Across 454 stations, Premium Diesel ranges from 232.7c to 279.9c, so filling a 50-litre tank at the cheapest station saves about $12.50 over the state average. Over the past week the WA average has risen 16.5c.
Compare Premium Diesel across 454 stations in Western Australia. Updated 09:55 PM, 09 Sep 2026.
Over the past 90 days, Premium Diesel in Western Australia has averaged 221.3c per litre, peaking at 255.0c on 6 September and bottoming out at 191.3c on 23 June — a range of 63.7c. Over the past week the WA average has risen 16.5c. Timing a fill-up around that range matters: on a 50-litre tank, filling at the period low instead of the peak saves $31.85.
| Month | Average Premium Diesel |
|---|---|
| April 2026 | 258.9c |
| May 2026 | 231.3c |
| June 2026 | 202.0c |
| July 2026 | 209.7c |
| August 2026 | 250.4c |
The cheapest Premium Diesel price in Western Australia right now is 232.7c per litre, across 454 stations tracked. The cheapest suburb right now is Oakford at a 240.6c average across 2 stations. Filling a 50-litre tank at the cheapest station instead of a station charging the state average of 257.7c saves $12.50. See the live cheapest-stations list on this page for the exact station, address and suburb. Prices update twice daily from the official state government feed, so the cheapest station can change between the morning and afternoon updates — check again before you drive.
The current Western Australia average for Premium Diesel is 257.7c per litre — 1.0c below the national average of 258.7c. Prices at individual stations range from 232.7c to 279.9c, a spread of 47.2c that shows how much shopping around can save. Over the past week the WA average has risen 16.5c. Petrolmate computes this average from every station reporting Premium Diesel in Western Australia via the official government price feed, refreshed twice daily.
Solo is currently the cheapest brand for Premium Diesel in Western Australia at 240.5c per litre average across 3 stations. The gap between the cheapest brand (Solo, 240.5c) and the priciest in our list (EG, 259.7c) is 19.2c per litre — about $9.60 per 50-litre tank. Brand averages are recalculated twice daily from official price data, so the cheapest brand can change with the price cycle.
Over the past 90 days, Premium Diesel in Western Australia has averaged 221.3c per litre, peaking at 255.0c on 6 September and bottoming out at 191.3c on 23 June — a range of 63.7c. Over the past week the WA average has risen 16.5c. Monthly averages for the past half-year are published in the table on this page. All figures come from official Western Australia government price reporting, aggregated daily by Petrolmate.