Does Higher Octane Gas Make a Difference?

Yes, but only in the right engine or situation. Higher octane fuel primarily helps engines that are designed to need it—typically high-compression, turbocharged, or performance engines—and it can prevent knocking under heavy loads or extreme heat. For most vehicles that are engineered for regular 87-octane gasoline, using a higher octane won’t increase power, improve fuel economy, or extend engine life enough to justify the extra cost.

What Octane Really Means

Octane is a measure of a fuel’s resistance to “knock,” the premature combustion of the air-fuel mixture that can cause pinging sounds and, in severe cases, engine damage. In the United States, the number on the pump is AKI (Anti-Knock Index), shown as (R+M)/2; typical grades are Regular 87, Midgrade 89, and Premium 91–93. Many European and Asian markets post RON (Research Octane Number), which reads about 4–5 points higher than AKI for the same fuel.

How Engines Use Octane

Modern engines use knock sensors and computer-controlled ignition timing. If the fuel detonates too easily (low octane), the engine retards timing to avoid knock, reducing power and efficiency. If the fuel resists knock (higher octane), engines that are tuned for it can hold more optimal timing or higher boost, delivering rated performance and efficiency.

When Higher Octane Is Required vs. Recommended

Automakers specify either “Required” or “Recommended” octane in the owner’s manual and on the fuel door. This distinction matters because it determines whether premium is necessary all the time or only beneficial in certain conditions.

Required (Premium Fuel Only)

Engines labeled “Premium Fuel Required” typically have high compression ratios, forced induction (turbo/supercharging), or aggressive tuning. They are calibrated assuming premium octane; using lower octane can cause persistent knock, reduced performance, and may risk long-term engine stress. In some cases it can void warranty claims related to fuel.

Recommended (Premium Advisable)

“Premium Fuel Recommended” means the engine will run safely on regular but may deliver better acceleration or towing performance on premium. The engine’s control system will adapt, but the gains vary by model and conditions, and are often modest in everyday driving.

What Independent Tests Show

Consumer and industry testing over the past decade, including multiple AAA studies, consistently finds that using premium in vehicles designed for regular offers little to no measurable benefit in typical driving. In contrast, vehicles that require or recommend premium often show improved acceleration or sustained performance under load when fed higher octane, especially in hot weather.

Common Situations Where Octane Choice Matters

Drivers frequently wonder whether specific driving conditions justify paying for premium. The scenarios below outline when higher octane may be beneficial versus unnecessary.

Before reviewing the scenarios, it helps to consider how load, temperature, and altitude influence knock. Heavy loads and heat increase knock tendency; altitude can reduce it due to thinner air. With that in mind, here are common cases:

• High-performance or turbocharged engines marked “Premium Required”: Always use premium (91–93 AKI). The engine’s rated power assumes it.
• Engines marked “Premium Recommended”: Use premium for maximum performance, towing, hot-weather mountain driving, or track use; regular is acceptable for normal commuting.
• Towing or carrying heavy loads in a vehicle rated for regular: If you hear pinging or the manual allows, stepping up one grade (e.g., 89) can help in hot conditions.
• High altitude driving: Lower air density reduces knock; many mountain regions sell 85–86 AKI as “regular.” Use the fuel grade your manual specifies for altitude; if unsure, stick with 87 or what the manufacturer lists as the minimum.
• Older vehicles without knock sensors: If you detect persistent pinging under load on regular, a higher octane may be a safer choice.
• Cold vs. hot weather: Heat promotes knock; premium can be more noticeable in very hot climates during strenuous driving.

Overall, match the fuel to your manufacturer’s guidance and driving demands. When in doubt, a single-step increase in octane during heavy-load or high-heat use can mitigate knock without committing to premium year-round.

Performance, MPG, and Cost

For cars built for regular, switching to premium rarely increases horsepower or fuel economy in everyday use. Studies show any MPG gain, if present, is typically within testing noise. For engines that are tuned to leverage higher octane, premium can unlock the advertised power and maintain efficiency under load by avoiding timing retard. The cost-benefit equation depends on fuel price spreads in your area and how often you drive in conditions that induce knock.

Fuel Quality, Detergents, and “Top Tier” Gas

Octane and detergent packages are separate issues. Detergents help keep injectors and intake valves clean; octane controls knock resistance. “Top Tier” certification indicates stronger detergent additives across all grades (regular to premium) at participating brands. Choosing Top Tier fuel can benefit engine cleanliness regardless of octane. If your engine is direct-injected, consistent use of quality detergents is especially helpful in reducing deposit formation.

Ethanol, Energy Content, and Octane Boosters

Ethanol blends (like E10) typically have slightly less energy per gallon than pure gasoline but often provide higher octane and cleaner combustion. That can be advantageous in engines calibrated for it. Over-the-counter octane boosters can raise octane marginally, but results vary; they’re generally unnecessary unless a manufacturer or tuner specifies them for modified engines.

Myths and Facts

Misinformation around octane can lead to unnecessary spending or incorrect fuel choices. The following points address common misconceptions and realities.

• Myth: Premium gas has more energy and makes any car faster. Fact: Octane isn’t energy content; it’s knock resistance. Extra octane doesn’t add power unless the engine can use it.
• Myth: Premium always keeps your engine cleaner. Fact: Detergent level, not octane, governs cleanliness. Look for Top Tier fuels in any grade.
• Myth: Using regular once in a premium-required car will destroy the engine. Fact: The ECU will usually pull timing to protect the engine, but expect reduced performance. Do not make it a habit.
• Myth: Higher octane improves fuel economy in all cars. Fact: Gains are rare and typically appear only in engines designed to benefit from higher octane under knock-prone conditions.

Understanding what octane does—and what it doesn’t—helps you choose fuel based on engineering needs rather than marketing claims.

How to Know What to Use

The most reliable source is your owner’s manual and the sticker inside the fuel door. Many modern turbocharged cars clearly state “Premium Required” or “Recommended.” If you ever hear persistent pinging on the specified grade, have the vehicle checked; knocking can also signal mechanical issues.

Bottom Line

Use the octane your manufacturer specifies. If it’s required, don’t skimp. If it’s recommended, premium can help in demanding conditions but isn’t mandatory for daily commuting. If your car is built for regular, higher octane almost never pays off.

Summary

Higher octane fuel matters when an engine is designed to exploit it or when conditions push the engine toward knock. It doesn’t add power or MPG to engines built for regular use. Follow your manual, consider Top Tier fuel for detergents, and step up in octane only when your vehicle or driving conditions call for it.

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.

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.

Will putting higher octane fuel in a car make it faster?

No it won’t. Cars only use the octane for which they are designed. Running higher octane gas has no benefit.

What happens if you put 91 gas in an 87 car?

Putting 91-octane gas in a car designed for 87-octane fuel will likely not harm the engine but will cost more without providing any performance benefits. Modern cars with advanced electronic fuel management systems can automatically adjust engine timing to accommodate the higher octane fuel. For most vehicles, the only noticeable difference will be a slightly lighter wallet, as you are paying for fuel you don’t need. 
What to expect:

• No engine damage: Higher octane fuel is designed to resist knocking, which is premature ignition of the fuel-air mixture. In a car designed for lower octane fuel, the engine’s computer (ECU) will sense the higher octane fuel and adjust the ignition timing and fuel injection to prevent potential issues. 
• Wasted money: You are essentially paying more for a feature (higher octane) that your car’s engine doesn’t require to function correctly. 
• No noticeable performance increase: You will not experience increased horsepower or improved performance, as the engine is not designed to take advantage of the higher octane. 
• No immediate performance decrease: In most modern vehicles, the change in octane will be handled so smoothly by the car’s computer that you likely won’t notice any change in how the vehicle runs. 

What to do:

• Don’t worry: For a one-time mistake, there is no cause for alarm. 
• Continue with your normal fuel: The next time you fill up your tank, you can switch back to your car’s recommended 87-octane fuel without any issues. 
• Check your owner’s manual: While it’s generally not harmful to use higher octane fuel, always refer to your car’s owner’s manual for specific recommendations on fuel octane ratings.