Falling oil prices do not always deliver equivalent savings at the bowser. Refining costs, shipping, exchange rates and local market conditions all influence what Australians pay for petrol and diesel. The effects extend beyond filling the tank. Higher fuel costs can lift inflation, squeeze household budgets and put company earnings under pressure.
Crude oil vs. the pump
Oil headlines usually refer to unrefined crude, which must be processed into petrol and diesel before it can fuel vehicles. Prices for these finished products can move differently from crude prices. The difference between crude and refined-fuel prices is known as the ‘crack spread’. Refinery closures, maintenance, supply disruptions and strong demand can widen that spread, keeping petrol and diesel expensive even when crude prices fall. More crude supply alone may therefore offer limited relief if refining or distribution remains constrained.
Diesel and the global economy
Diesel powers much of the machinery and transport behind mining, agriculture and freight. Higher diesel prices raise costs across supply chains, putting pressure on businesses to increase prices or accept lower margins. They also leave less money available for spending, investment and hiring.
Why Australia is exposed?
Australia relies on imported transport fuels, with local prices linked to Singapore refined-fuel benchmarks. A weaker Australian dollar makes fuel priced in US dollars more expensive, potentially offsetting overseas price falls. Shipping costs, taxes, retail competition and local price cycles also shape the final bowser price. It could also be argued that poor planning from successive Australian governments, have left us exposed to global trade disruptions and an inability to refine oil to the levels required. Neither of these issues can be addressed quickly.
Refining constraints are only one influence, not a complete explanation for fuel prices. For Australian inflation, the critical questions are how far prices rise, how long increases last and how widely they flow through the economy.
How fuel flows through to Australian inflation?
The first effect is direct. Automotive fuel is part of the Consumer Price Index (CPI), so higher petrol and diesel prices lift headline inflation, all else being equal. But high prices are not the same as continuing inflation. If fuel prices jump and then stabilise, that increase eventually drops out of the annual comparison—even though filling the tank remains expensive. Lower inflation therefore does not necessarily mean lower living costs.
The second effect is indirect. Higher diesel costs can make groceries, farm production, construction and deliveries more expensive. These pressures reach consumers later through freight surcharges or revised contracts. Pass-through is not automatic: competition, fuel hedging and customers’ willingness to pay determine how much businesses recover and how much they absorb in lower margins. This is one reason why a high number of small businesses are struggling.
The third effect is weaker purchasing power. Higher essential transport bills leave households less for dining out, entertainment and other discretionary spending. This can slow demand and restrain price rises elsewhere, meaning fuel can lift inflation while weakening growth. The squeeze is uneven: households with long commutes or few transport alternatives may face greater pressure than the national CPI suggests.
What it means for the RBA and interest rates?
Interest rates cannot increase oil supply or remove shipping bottlenecks. The Reserve Bank’s concern is whether a fuel shock becomes broader, persistent inflation. Alongside headline CPI, it monitors underlying measures such as the trimmed mean, which reduces the influence of unusually large price movements rather than always excluding fuel. Transport costs that spread across many goods and services can also lift underlying inflation.
Repeated price increases and rising inflation expectations would make a sustainable return to the RBA’s 2–3 per cent target harder. Yet higher fuel prices do not automatically mean higher interest rates or rule out future cuts. The RBA must balance inflation persistence against weaker spending, employment and growth.
The indicators to watch are refined-fuel prices, the Australian dollar, business cost pass-through and the breadth of underlying inflation. Cheaper fuel would ease budgets but would not resolve domestic inflation pressures on its own. Equally, one fuel-driven CPI result is not a reliable guide to the interest rate outlook.
What this means for markets and earnings?
Higher fuel costs test companies’ ability to protect margins. Transport operators, airlines, retailers and manufacturers with significant logistics needs can face earnings pressure, particularly when they cannot pass costs on to customers.
Refiners and integrated energy businesses may benefit from wider refining spreads, although outcomes depend on their operations and costs. Businesses with less exposure to physical supply chains, or greater pricing power, may be better placed to defend earnings.
This update is general information only and does not consider your personal objectives, financial situation or needs. You should consider the appropriateness of any strategy in light of your circumstances and seek professional financial advice before making investment decisions.