Is premium gas 89 or 91?

Premium gasoline is not a universal number; it depends on where you are and which octane scale your fuel uses. In the United States and Canada, premium is typically 91–93 AKI, while 89 is usually considered midgrade. In many other regions, premium is labeled by RON and commonly sits around 95–98 RON. Always check local labeling and your vehicle’s manual for the correct grade.

Understanding octane ratings: AKI vs RON

Octane ratings measure a fuel’s resistance to knocking under compression. In North America, the pump numbers reflect AKI (anti-knock index). In Europe, Asia and many other markets, the numbers are given as RON (research octane number). AKI and RON are not directly interchangeable, though higher numbers generally indicate greater resistance to knock. For practical purposes, a typical US premium of 91–93 AKI roughly corresponds to higher-RON grades used abroad.

Here are the core distinctions drivers should know about:

• AKI (used in the US/Canada) vs. RON (used in Europe and many other regions) measure the same idea with different scales and testing methods.


• Premium grades are simply the higher-octane options offered by retailers; “regular,” “midgrade,” and “premium” reflect commonly used bands within each system.


• Engines with high compression, turbocharging, or advanced timing often benefit more from the recommended high-octane fuel; engines designed for regular may not gain noticeable advantages from switching to premium.


• Reading the owner’s manual or the fuel-filler door sticker is the best way to know which grade your vehicle needs.

In short, higher octane helps prevent knocking in certain engines, but it does not create more energy or power in engines that are designed to run on regular fuel.

Regional norms for premium gasoline

Fuel labeling and common practices vary by region. The overview below reflects typical industry practice as of 2024–2025.

• United States and Canada: Premium is typically 91–93 AKI; 89 AKI is commonly available as midgrade; regular is usually 87 AKI. Some stations offer 94–95 AKI blends for specialty or performance fuels.


• Europe, parts of Asia, Africa and Oceania: Premium is usually 95–98 RON. In many markets, 95 RON is the standard “regular unleaded,” with 98 RON or higher sold as premium or high-performance grades.


• Other markets (including parts of the Asia-Pacific region): Premium grades commonly range from about 92–98 RON depending on country and retailer. Always verify local labeling and availability.

Because octane labeling is country-specific, it’s essential to match the fuel to what your car’s manufacturer recommends and to use the grade indicated on the fuel door or in the owner’s manual.

What this means for drivers

When should you use premium gasoline?

Use the octane grade recommended by your owner’s manual or the fuel-door sticker. If your engine requires high octane (for example, many turbocharged or high-compression engines), using premium helps avoid knocking and protects performance. If the manual lists regular, you won’t typically gain measurable benefits from using premium, and you’ll just pay more at the pump.

Cost and efficiency considerations

Premium gas costs more per gallon. In many vehicles, especially those not requiring high octane, the performance or efficiency gains are small or nonexistent. In engines designed for higher octane, benefits can include smoother operation and maintained performance under load, but this is not universal.

Practical tips for choosing a grade

Always verify the grade at the pump relative to your vehicle’s requirements, and don’t confuse regional labeling. If you notice knocking or pinging with regular fuel in a high-performance engine, move to the recommended premium. Conversely, if your car is designed for regular and runs smoothly on it, there’s often little reason to pay extra for premium.

Summary

Octane labeling varies by region. In the United States and Canada, premium is typically 91–93 AKI, with 89 AKI usually considered midgrade. In Europe and many other markets, premium commonly sits at 95–98 RON. Always follow the octane grade recommended by your vehicle’s manufacturer, and remember that higher octane only benefits engines that require it; using premium in a vehicle that doesn’t need it may not improve performance or fuel economy. Check your manual and local pump labeling to choose the right grade for your car.

Is premium fuel 89 or 91?

Regular (the lowest octane fuel–generally 87) Midgrade (the middle range octane fuel–generally 89–90) Premium (the highest octane fuel–generally 91–94)

What happens if you put 89 gas in a premium car?

Putting 89-octane gas in a car that requires premium fuel will likely result in reduced engine performance and possibly a slight decrease in gas mileage, though a one-time use is unlikely to cause lasting damage. Modern cars have knock sensors that can adjust the engine's timing to compensate for the lower octane, but this can cause the engine to run rough, feel sluggish, and potentially run hotter than usual. It is best to follow the manufacturer's recommendation for the correct octane fuel.
 
What to expect

• Reduced performance: The engine's knock sensor will detect the lower octane and retard ignition timing to prevent knocking or pinging. This will lead to less power and acceleration. 
• Lower fuel efficiency: You may experience a decrease in gas mileage because the engine is working less efficiently. 
• Potential for engine noise: A slight knocking or pinging noise from the engine is possible, especially under load. 
• No immediate catastrophic damage: A single instance of using 89-octane gas in a premium car is unlikely to cause immediate, catastrophic engine damage due to the engine's ability to adjust and compensate. 
• Risk of damage with long-term use: Consistently using a lower-than-recommended octane fuel can lead to engine damage over time, which may not be covered by your warranty. 

What to do

• If it's an emergency: You can safely use 89-octane in a pinch, but top off your tank with the correct premium fuel on your next visit. 
• If you've already filled up: Continue to use 89-octane until your tank is nearly empty, then switch back to premium to help flush the system. 
• Consult your owner's manual: Always refer to your car's owner's manual to determine the recommended octane for your vehicle. If it says to use premium, it is best to stick with premium fuel for optimal performance and engine health. 

What happens if I use 89 instead of 91?

Putting 89 octane gas in a 91 octane car will likely lead to reduced engine performance, such as sluggishness and decreased fuel economy, and may cause "knocking" or "pinging" noises, especially under hard acceleration. The car's engine control unit (ECU) will likely adjust timing to compensate for the lower octane to prevent engine damage, but this adjustment results in lower power and efficiency. While a single instance may not cause lasting damage, long-term use could lead to component wear and potentially void the manufacturer's warranty. 
Potential consequences

• Knocking or pinging: The lower octane fuel may detonate prematurely, causing a knocking or pinging sound. Modern engines have sensors that detect this and adjust the timing, but this reduces performance. 
• Reduced performance: You may notice less power, slower acceleration, and a generally "sluggish" feeling from the engine. 
• Lower fuel economy: The engine will be less efficient, resulting in slightly lower miles per gallon. 
• Engine damage (long-term): While a single instance is unlikely to cause permanent damage, consistently using a lower octane than required can cause wear and tear on engine components over time. 

What to do if you accidentally put 89 octane in your car

1. Don't panic: For a single instance, the engine's knock sensors will likely make adjustments to prevent damage. 
2. Drive normally: You can continue to drive the car, but avoid hard acceleration to minimize the risk of knocking. 
3. Fill up with the correct fuel: At your next fill-up, add 91 octane gas. As you continue to drive and add the correct fuel, the lower octane fuel will be mixed with higher octane fuel, raising the overall octane level in your tank. 
4. Consult your owner's manual: Check your car's owner's manual for specific recommendations and what to do in this situation. 

What's the difference between 89 and 91?

The main difference is that 91 octane is more resistant to engine knock than 89 octane, making it the recommended fuel for high-compression, turbocharged, or performance engines. Using 89 octane in a vehicle that requires 91 may cause reduced performance, lower fuel efficiency, and potential damage over the long term due to knock. While using 89 is generally not damaging, sticking to the manufacturer's recommendation is best for optimal performance and engine longevity.
 
This video explains the difference between octane ratings and when to use them: 53sJason’s JourneysYouTube · Dec 2, 2024
89 octane

• Category: Midgrade gasoline 
• Characteristics: Has better knock resistance than regular (87 octane) gasoline. 
• Use case: Suitable for many standard vehicles, but not recommended for those with high-performance engines that require premium fuel. 

91 octane

• Category: Premium gasoline 
• Characteristics: Higher resistance to knocking, which allows for higher compression ratios in engines. 
• Use case: Recommended for most turbocharged and high-compression engines, as they are designed to take advantage of its properties for optimal performance and efficiency. 

This video compares the performance of 89 octane vs 91 octane gas in a BMW: 59sEuroDrivenYouTube · Nov 30, 2020
Which one should you choose?

• Check your owner's manual: This is the most important step. The manufacturer will specify the minimum octane level required for your vehicle. 
• If your car requires 89: You can use 89 octane without issue. 
• If your car requires 91: It is best to use 91 octane. Using 89 may result in reduced performance and fuel economy, and could lead to engine damage over time. 
• If you're unsure: It's always safer to use the higher octane fuel recommended by the manufacturer to avoid potential issues.