Is Higher Octane Gas Better for Cars?

No—higher octane gas isn’t inherently “better” for most cars. It’s beneficial or necessary only for engines designed to use it to prevent knock and achieve their rated performance. If your owner’s manual specifies regular (87 AKI) fuel, paying extra for premium typically delivers no meaningful gains in power, fuel economy, or engine life. The right choice is the grade your automaker specifies, with higher octane reserved for engines that require or recommend it or for specific high-load conditions.

What Octane Really Means

Octane is a measure of a fuel’s resistance to engine knock (pre-ignition). In the U.S. and Canada, the octane shown on the pump is AKI (Anti-Knock Index), labeled as (R+M)/2. Common grades are 87 (regular), 89–90 (midgrade), and 91–93 (premium). Higher octane does not add energy to the fuel; it simply tolerates more compression and advanced ignition timing before knocking, which matters in high-compression or turbocharged engines. Modern engines have knock sensors that adjust timing to protect the engine, but using fuel below a required rating can still reduce performance and, in severe cases, risk damage.

Who Actually Benefits From Premium

Premium fuel makes a difference when the engine is designed or calibrated to take advantage of higher knock resistance. Automakers typically mark this as “premium required” (must use 91+ AKI) or “premium recommended” (91+ AKI for best performance, but 87 AKI is acceptable with reduced output).

Below are common scenarios where higher octane is required or pays off:

• High-compression, turbocharged, or supercharged engines whose manuals state “premium required” (often 91+ AKI).
• Performance trims tuned for maximum horsepower/torque; premium helps maintain rated specs.
• “Premium recommended” engines: premium restores full power and can prevent timing pull; using regular may cut peak output by roughly 5–10% and slightly reduce fuel economy (often 0–3%).
• Heavy loads, hot weather, high-speed mountain driving, or towing in turbocharged engines, which can increase knock tendency.

In short, premium is valuable when an engine’s design or operating conditions push it toward knock; otherwise, the benefit is negligible.

When Higher Octane Is Unnecessary

If your manual specifies regular (87 AKI), premium usually won’t make the car quicker, more efficient, or longer-lived. Independent testing has repeatedly found no consistent performance or mpg benefit in engines designed for regular. What matters more for engine cleanliness is detergent quality (for example, Top Tier certification), which is independent of octane grade.

Common misconceptions include the following:

• Higher octane equals more power in any car: false—octane isn’t an energy content rating.
• Premium keeps engines cleaner: cleanliness depends on detergents, not octane; look for Top Tier gasoline at any grade.
• Premium lasts longer in storage: shelf life relates to volatility, ethanol content, and stabilizers more than octane.
• High altitude justifies 85 octane in modern cars: many manufacturers still specify 87 AKI minimum even in mountain states where 85 is sold.

These points underscore that octane is about knock resistance, not overall fuel quality or longevity.

Using Lower or Higher Than Specified

If You Use Lower Than Required

In engines marked “premium required,” using lower octane can trigger knock, force aggressive timing retard, reduce performance, illuminate warning lights, and in extreme cases risk engine damage. It may also complicate warranty coverage for related issues. In “premium recommended” engines, lower octane is usually safe but will reduce power and responsiveness.

If You Use Higher Than Required

In engines designed for regular, premium rarely delivers noticeable gains because the engine management won’t advance timing beyond its maps. It’s safe, but typically a waste of money. Some drivers might notice marginal smoothness under heavy load, but it’s not a reliable benefit for everyday driving.

Regional and Fuel Blend Nuances

Octane availability varies by region (some areas sell 91 as premium; others offer 93). In certain mountain states, 85 AKI is still sold, but many modern vehicles still require at least 87—even at altitude. Ethanol blends complicate the picture: E10 (common) is fine for most vehicles; E15 is approved only for 2001+ gasoline cars and light trucks; E85 (roughly 100–105 AKI) is for flex-fuel vehicles and can boost power in engines tuned for it but reduces miles per gallon. Detergent quality (e.g., Top Tier) is separate from octane and worth prioritizing.

Here are practical fueling tips to match octane to your needs:

• Check your fuel door and owner’s manual: “premium required” means 91+ AKI is mandatory; “recommended” means 91+ for best performance.
• If you hear persistent pinging/knock on the correct grade, step up one grade and have the engine inspected.
• Prioritize Top Tier gasoline at any octane to help keep injectors and valves cleaner, especially in direct-injection engines.
• Avoid 85 AKI unless your manufacturer explicitly permits it at altitude; many do not.
• For towing, track use, or extreme heat in turbocharged engines, consider using the next higher octane to prevent timing pull.
• Mixing grades is fine; the resulting octane is the weighted average of what you add.

Following these practices protects your engine, preserves performance, and avoids unnecessary fuel costs.

Bottom Line

Higher octane gas is not categorically “better.” Use it when your vehicle requires or recommends it, or when operating conditions demand extra knock resistance. For most cars designed for regular, premium adds cost without meaningful benefit; focus instead on using the correct grade and a reputable, detergent-rich fuel.

Summary

Octane measures knock resistance, not fuel quality or energy. Premium pays off in engines that require or can exploit it—especially high-compression and turbocharged designs or under heavy load and heat. If your car is built for regular, premium won’t improve performance or mpg in a meaningful way. Check your manual, respect “required” versus “recommended,” and prioritize good detergent fuel over unnecessary octane.

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

The Federal Trade Commission recommends using regular gasoline for most standard cars and notes that: “In most cases, using a higher octane gasoline than your owner’s manual recommends offers absolutely no benefit. It won’t make your car perform better, go faster, get better mileage, or run cleaner.”

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.

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.

Will my car run better with higher octane gas?

No. Assuming that you use fuel which meets the manufacturers specifications, a higher octane rating will be of no benefit to the engine. The required octane rating is primarily determined by the compression ratio.