Which gas is better, 87-89 or 93?
For most cars, regular 87 octane gasoline is the recommended choice; 93 octane premium is better only for engines designed for high octane or for performance driving, and it typically comes with a higher price tag.
Gasoline octane measures a fuel’s resistance to knocking, not how much energy a fuel contains. Higher octane prevents pre-ignition in certain engines, but it does not automatically deliver more power or better fuel economy in every vehicle. The right octane depends on engine design, timing, and operating conditions, as well as cost considerations. This article explains when each octane level makes sense and how drivers can decide what to use.
Understanding octane and engine design
Before we dive into lists, it’s important to know that octane rating is about knock resistance, not energy content. Modern engines can adjust timing and fueling to accommodate different octanes, but the engine’s compression ratio and calibration largely determine whether higher octane yields a benefit.
The numbers and what they mean
87, 89, and 93 refer to octane ratings used in the United States to indicate resistance to detonation. Higher numbers resist knocking better, which can allow more advanced timing in certain engines.
Now the guidance, organized into practical scenarios.
When regular 87 or mid-grade 89 octane is appropriate
The following scenarios commonly apply to vehicles designed for lower octane fuels; consider these factors to decide if you should stick with 87-89 rather than paying for 93.
- Designed for regular octane: Most mainstream cars specify 87 octane in the owner's manual; using higher than required usually yields no sustained performance gains.
- Cost consideration: 87-89 are typically cheaper than 93, offering immediate fuel-cost savings if performance gains are not expected.
- Standard driving: Everyday commuting and steady speeds usually do not benefit from higher octane; variations in driving style, heat, or altitude have limited impact unless the engine requires it.
- Detonation risk is low at recommended octane: If your engine runs smoothly with no knocking under load, you are unlikely to gain by using higher octane.
Concluding this section: For most vehicles that specify 87 octane, there is little to gain from using 93; it mainly increases fuel cost without meaningful performance improvements.
When 93-octane or higher is beneficial
The following are common conditions where higher octane could offer advantage, depending on engine design and operating conditions.
- High-compression or performance engines: Engines with high compression ratios or turbocharged/supercharged setups often require higher octane to prevent knocking and to enable optimized timing for power.
- Performance driving or hot climates: In spirited driving or under heavy loads (towing, steep climbs) in hot conditions, higher octane can reduce knocking and maintain performance.
- Manufacturer recommendation: Some engines are engineered to run on premium only; using 87 may trigger knocking, reduced performance, or even engine protection measures.
- Detergents and additives: Premium fuels often come with different additive packages, which can contribute to engine cleanliness and longevity, though this effect is not guaranteed and varies by brand.
Concluding this section: If your vehicle requires or benefits from high octane, 93 may be worth the extra cost. Always rely on the manufacturer’s recommendation and your own driving needs.
Cost, availability, and other considerations
Beyond octane rating, there are practical factors to weigh when choosing fuel.
- Price gap: Premium fuels can cost significantly more per gallon; assess whether the potential performance or reliability benefits justify the extra expense based on your driving pattern.
- Ethanol content: Some premium fuels include ethanol blends (e.g., E10). In some regions, premium may have higher or lower ethanol content, which can subtly affect mileage and cold-weather performance.
- Fuel system and detergents: Differences in additive packages vary by brand; consistent use of a reputable brand is often more important than octane alone for long-term engine health.
- Engine age and condition: Older engines or those with carbon buildup or timing issues may respond differently to octane changes; consult a mechanic if you’re unsure.
Conclusion: Choose octane based on the vehicle's requirements, not on a belief that higher octane automatically delivers more miles per gallon or power.
How to choose the right octane for your car
To avoid guesswork, follow a simple decision flow based on official recommendations and practical testing with your own driving.
- Check the owner’s manual or fuel-filler label to confirm the recommended octane. Use the minimum recommended octane for normal operation.
- Listen for engine knocking: If you hear pinging or knocking under load, and you’re not using the recommended octane, switch to a higher-octane fuel as soon as feasible.
- Be mindful of your engine’s design: High-performance or newer engines with knock sensors often optimize timing across octane grades; your gains from stepping up may be modest unless you’re demanding peak performance.
Final thought: Use the octane your vehicle requires; higher octane is not a universal upgrade.
Summary
Most drivers benefit most from sticking to the octane specified by the manufacturer. Higher-octane fuel protects high-compression and performance engines from knocking and can enable optimal timing in certain conditions, but it comes at a higher price and may not improve efficiency or power in everyday driving. Always weigh cost, driving style, and engine design when choosing between 87-89 and 93.
