Do I really need to use 98RON (premium) fuel once my car is tuned?

Short answer: yes, you need 98RON premium fuel. This isn't a suggestion or a preference. It's a hard requirement for most Stage 1 and Stage 2 tunes on modern turbo Euro engines.

Why Fuel Octane Matters So Much

Octane ratings measure fuel's resistance to knock, which is uncontrolled combustion in the cylinder. Higher boost pressures on tuned engines create more heat and more pressure, increasing the likelihood of knock. Higher-octane fuel resists knock better, allowing the engine to run the aggressive timing and boost that makes the power.

When you run lower-octane fuel in a tuned engine:

• The ECU detects knock and pulls timing to protect the engine
• You lose power, often significantly
• Over time, consistent knock can damage piston rings and bearings
• The engine runs hotter than intended

What Happens With 95RON or Lower

Australian 95RON is standard premium. On many Stage 1 maps, it's borderline acceptable if the tuner has programmed specifically for it. But most quality European maps target 98RON, which means 95RON causes the ECU to pull timing.

The effect is most noticeable under load: hard acceleration, highway pulls, and climbing hills. Your data log might hit 350hp on 98RON, but drop to 310hp on 95RON. That's a significant loss, equivalent to throwing away a major part of what you paid for.

The 98RON Reality in Australia

Australian fuel quality is generally good, but it varies. Regional bowsers and smaller servo chains sometimes have fuel that's closer to spec on the label than in the tank. If you're running a tuned car and notice knock, hesitation, or power loss, the fuel is the first thing to question.

Shell V-Power, BP Ultimate, and Mobil 98 are consistently good. Budget fuels from less-known chains are a gamble not worth taking with a tuned engine.

What About E85 or Other Blends

E85 ethanol mixes are increasingly popular in the tuning scene. They offer higher octane (100+) but require different mapping. You can't just fill up with E85 and expect your Stage 1 petrol map to work. It won't run properly without a dedicated flex-fuel tune or conversion.

The Sherzad Haus Approach

We write our tunes to Australian 98RON specs as the baseline. Running 95RON will reduce your power results. Running 98RON where it's actually 98 (or higher) gives you the full benefit.

We recommend always filling with quality 98RON from major servo chains. It's a small additional cost for big peace of mind.

Book an inspection and we'll run your car and data log it to see exactly what it's doing with proper fuel.