Is High-Octane Petrol Better?

High-octane petrol is better only for engines that are designed or tuned to need it; for most cars that specify regular fuel, it delivers no meaningful benefit in performance, economy, or cleanliness and simply costs more. The right answer depends on your engine’s compression, turbocharging, and what your owner’s manual says—“required” versus “recommended” makes all the difference.

What “Octane” Actually Measures

Octane is a measure of a fuel’s resistance to knock (also called detonation), the uncontrolled combustion that can occur under pressure and heat. Higher octane allows an engine to run more spark advance, higher compression, or more turbo boost before knock occurs. It does not mean the fuel contains more energy. Different regions rate octane differently: the U.S. and Canada use AKI (Anti-Knock Index, or (R+M)/2), while much of the world uses RON (Research Octane Number). Roughly, 91 AKI ≈ 95 RON; 93 AKI ≈ 98 RON.

When High-Octane Fuel Is Better

The following situations are where premium/high-octane petrol genuinely provides advantages because the engine can exploit its higher knock resistance.

• The manufacturer states “premium required” (often on the fuel door or in the owner’s manual), common for high-compression, turbocharged, or performance engines.
• Vehicles calibrated to make more power on higher octane; modern ECUs advance timing and increase boost until knock is detected, so premium can unlock advertised horsepower/torque.
• Heavy loads or harsh conditions—towing, steep climbs, very hot weather—where engines run closer to knock limits.
• Some small turbocharged direct-injection engines that are prone to low-speed pre-ignition (LSPI); higher octane can reduce events when the automaker recommends it for severe service.
• Track use or spirited driving where sustained high cylinder pressures demand extra knock margin.

In these cases, high octane is not just “better”—it’s necessary to achieve rated performance and to protect the engine from damaging knock.

When High-Octane Fuel Is Not Better

For many everyday vehicles designed for regular petrol, premium adds cost without realistic gains in normal use.

• Engines that specify regular (e.g., 87 AKI/91–95 RON) and do not advance timing further on premium won’t make extra power or economy.
• City commuting and light-load driving seldom push an engine to knock limits, leaving no room for premium to help.
• Engine “cleanliness” is a function of detergent additives (look for Top Tier certification), not octane itself.
• Any fuel-economy change is typically negligible; studies often find 0–1% change in cars designed for regular, while the price premium is usually 10% or more.
• If your vehicle says “premium recommended,” you may feel a bit more punch in hot weather or under load, but routine daily driving often shows no measurable difference.

In these scenarios, paying for premium is usually a waste of money with no protection or performance upside.

Power, Efficiency, and Engine Longevity

Running lower octane than required can cause knock that forces the ECU to pull timing, cutting power and potentially raising exhaust temperatures; persistent heavy knock risks engine damage and may void warranty. Using premium in an engine calibrated for it can add a few percent in power and responsiveness, especially under load. Using premium in an engine designed strictly for regular typically does not extend engine life or improve fuel economy. Independent tests (e.g., AAA, Consumer Reports) have repeatedly found minimal benefit where premium is not required.

The Money Math

Premium often costs 10–20% more per liter. Even if an engine that “recommends” premium gains 1–3% in efficiency or performance under certain conditions, the price gap usually outweighs the benefit for routine driving. For cars that require premium, the cost is part of achieving the engine’s rated output and avoiding knock—non-negotiable.

Common Myths vs. Facts

Misconceptions abound at the pump. Here’s how the most frequent claims stack up.

• Myth: Premium has more energy. Fact: Octane is knock resistance, not energy content; premium doesn’t inherently deliver higher MPG.
• Myth: Premium always cleans your engine better. Fact: Detergent packages—not octane—do the cleaning. Choose Top Tier gasoline regardless of grade.
• Myth: Mixing grades harms the car. Fact: Blending simply yields an intermediate octane; it’s safe if the result meets your minimum requirement.
• Myth: Premium prevents all knock. Fact: It raises knock resistance, but heat, deposits, and incorrect tuning can still cause knock.
• Myth: All performance cars need premium. Fact: Many do, but some modern engines are optimized for regular; always check the manual.

Separating marketing from engineering helps you buy the right fuel for your vehicle and budget.

How to Choose the Right Fuel

Use these practical steps to decide whether high-octane petrol makes sense for your vehicle and driving conditions.

1. Check the fuel door and owner’s manual for “minimum octane,” and whether premium is required or merely recommended.
2. If “required,” use it every fill. If “recommended,” consider premium for hot weather, mountain driving, towing, or spirited use.
3. Listen for audible knock/ping under load; if present on the specified fuel, have the car checked and consider trying the next higher octane.
4. Prioritize Top Tier detergent fuel to keep injectors and valves cleaner; this matters more than octane for cleanliness.
5. Evaluate cost vs. benefit: try a couple of tanks of premium in varied conditions; if you don’t notice smoother operation or better response where it matters, stick with regular.
6. For small engines and motorcycles, use the exact octane and ethanol guidance specified by the manufacturer.

Following these steps aligns your fuel choice with your vehicle’s needs while avoiding unnecessary expense.

Octane Numbers by Region: Decoding the Pump

Because octane is labeled differently around the world, it helps to translate ratings so you buy the correct grade when traveling or reading international advice.

• U.S./Canada (AKI): Regular 87, Mid-grade 89, Premium 91–93.
• Europe/UK/Australia (RON): Regular 95, Premium/Super 97–99 (sometimes 98).
• Rule of thumb: 91 AKI ≈ 95 RON; 93 AKI ≈ 98 RON. Always meet or exceed your car’s minimum requirement when converting.

Using the correct conversion ensures you don’t underfuel (risking knock) or overpay for unnecessary octane.

Environmental and Maintenance Considerations

Octane itself doesn’t make fuel cleaner-burning in a way that reduces tailpipe emissions across the board. Engines running the correct octane tend to operate more efficiently under load, which can modestly help emissions in those conditions. For deposit control, look for Top Tier certification; it specifies robust detergent additives across all octane levels. Ethanol content also matters: higher ethanol blends raise octane but slightly reduce energy per liter, which can trim MPG—separate from the octane effect.

Bottom Line

High-octane petrol is a tool, not a treat. It’s essential when your engine is engineered for it and largely superfluous when it isn’t. Let the owner’s manual and your driving demands guide the choice, and focus on fuel quality (detergents) over octane for cleanliness.

Summary

High-octane petrol is better only for engines that require or can exploit it—typically high-compression or turbocharged designs, heavy-load or high-heat driving, or when the manufacturer says “premium required/recommended.” For vehicles designed for regular, premium rarely improves performance, fuel economy, or engine life and usually isn’t worth the extra cost. Always meet the stated minimum octane, prioritize reputable Top Tier fuel, and let your real-world driving conditions decide whether premium pays off.

Is 93 octane really better than 87?

No, 93 octane gas isn’t inherently “better” than 87 octane gas; rather, it’s a higher-octane fuel that is only beneficial for engines designed to require it, typically high-compression or high-performance vehicles, to prevent engine knocking and detonation. For standard vehicles that recommend 87 octane, using 93 octane offers no performance benefit and is a waste of money. Always check your vehicle’s owner’s manual or the inside of the fuel door for the recommended octane level. 
Why Octane Matters

• Knocking and Detonation: Opens in new tabOctane is a measure of a fuel’s resistance to premature ignition or “knocking”. In a high-compression engine, if the fuel-air mixture ignites before the spark plug fires, it can create a damaging shockwave called detonation. 
• Engine Requirements: Opens in new tabHigh-octane fuel (like 93) is designed for engines that have high compression ratios and require more stable fuel to prevent this premature ignition and maintain optimal performance. 

When to Use 93 Octane

• Check Your Vehicle: Opens in new tabIf your car’s owner’s manual or fuel door states that 93 octane or premium fuel is required, then using it is essential. 
• High-Performance Engines: Opens in new tabVehicles designed with high-compression engines benefit from higher octane fuels for increased performance and to prevent engine damage. 

When 87 Octane is Fine

• Standard Engines: Most mainstream vehicles that do not have high-compression engines only recommend 87 octane. 
• No Performance Gain: Using 93 octane in a vehicle designed for 87 octane will not result in better performance or fuel economy; it will simply cost you more money. 

In summary: Use the fuel grade your car’s manufacturer recommends to ensure optimal performance, prevent engine damage, and avoid unnecessary costs.

What happens if I put 91 instead of 95?

Q: Can I use a lower octane fuel than the one recommended for my car? A: No, as it can produce things like loss of power or acceleration, loss of fuel economy, or a knocking or pinging sound in your engine.

Is there a difference between 93 and 95 petrol?

Generally, 95 octane petrol is more expensive than 93. If your car’s manufacturer recommends 93 octanes, using 95 might not provide a significant benefit to justify the extra cost. However, if your vehicle requires 95 octane, using 93 could lead to engine knocking and potentially expensive repairs.

Does putting 93 premium in 87 gas improve?

Nothing happens when you mix 93 (premium) and 87 (regular) octane gases. The mix is called “midgrade” gas. Some of the benefits of 93 gas include better engine health, reduced engine knock, better fuel economy, and more power. Note that your owner’s manual indicates what type of gas works best with your vehicle.