Petrol 91 vs 95 in NZ: which should you use?
Use the petrol grade specified for your car. If the manufacturer says 91 is suitable, paying extra for 95 usually gives no useful benefit. If the car requires 95, do not replace it with 91 to save money.
What do 91 and 95 mean?
The numbers are octane ratings. A higher number means the fuel can resist engine knock under greater pressure. It does not mean the fuel contains more energy or is automatically better for every car.
The safest places to check are the owner's manual and the label inside the fuel flap. If they are unclear, ask the vehicle manufacturer or its authorised dealer.
How much more does Petrol 95 cost?
Across the national weekly averages, Petrol 95 cost about 15.3 cents per litre more than Petrol 91 during 2025. The average gap in 2026 through 25 September was about 14.8 cents.
A 15 cent gap adds $7.50 to a 50 litre fill. That is worth paying when the engine requires 95. It is usually wasted when the engine was designed for 91.
Can a higher grade improve fuel economy?
Some engines designed to adjust for different grades may behave differently, but there is no general rule that 95 saves enough fuel to cover its higher price. The Motor Trade Association's guidance is straightforward: use the grade specified by the manufacturer.
What if you use the wrong grade?
Using a higher grade than required is normally a cost issue, not a danger. Using a lower grade than required can cause poor running or engine knock and may damage the engine. If you have used a lower octane grade than your car requires, follow the owner's manual or contact the manufacturer for advice.
Check the forecast for your grade
Petrol 91 and Petrol 95 usually move in the same broad direction, but not always by the same amount. Fill or Wait gives each grade its own forecast for next week and the week after.
Check the Petrol 91 and Petrol 95 forecasts →
Price gaps calculated from national weekly averages available on 2 October 2026. The grade specified for your vehicle always takes priority.