Five servos in Perth will sell unleaded fuel at least 20c/L cheaper than the average on Wednesday. Five servos in Perth will sell unleaded fuel at least 20c/L cheaper than the average on Wednesday. Credit: Stuart Quinn / The West AustralianFive servos in Perth will sell unleaded fuel at least 20c/L cheaper than the average on Wednesday. The average price of diesel in Perth will rise 1c to $2.27. At the height of the conflict and pressure on worldwide oil supply, unleaded petrol in Perth topped $2.50/L.