Should I use 87 or 89 gas?
Most drivers can safely use regular 87-octane gasoline. The practical answer is: stick with 87 unless your vehicle’s manufacturer specifies 89 or higher, or you notice engine knocking on 87.
What octane means and why it matters
Octane rating measures a fuel's resistance to knocking, a pinging or pre-ignition that can occur under compression in the engine. Higher-octane fuels resist knocking better, which can matter for engines with high compression or turbocharging. Using the octane your engine is tuned for helps maintain optimal timing and performance, but beyond that requirement, higher octane often yields little to no improvement in everyday driving.
Knock, timing, and performance
Modern engines use knock sensors and advanced engine control to adjust timing. In many cars, the difference between 87 and 89 octane is not dramatic unless the engine is designed to take advantage of higher octane. For the typical daily driver, the driver’s manual will indicate the recommended or minimum octane and that is usually sufficient for normal use.
When to use 87 octane
Here is a quick guide to situations where 87-octane gas is appropriate and commonly used.
- Vehicles whose owner’s manual lists 87 octane as the recommended or minimum fuel.
- Most modern sedans, crossovers, SUVs, and light trucks designed for regular unleaded gas.
- Engines with standard compression that do not require higher-octane fuel or that do not knock on 87.
- Drivers looking to minimize fuel costs, as 87 is typically cheaper than higher-octane options.
- Daily driving under normal conditions where no knocking or pinging is observed.
Choosing 87 octane for these scenarios is generally safe, reliable, and cost-effective.
When to consider 89 octane
There are specific circumstances where 89-octane gasoline may be beneficial or required by the vehicle’s design.
- Engines that specify 89 octane (or higher) in the owner’s manual, or vehicles that have a fuel door sticker indicating a higher minimum octane.
- Turbocharged or high-compression engines that can benefit from higher resistance to knocking, especially under heavy load or hot conditions.
- Instances of knocking or pinging on 87 octane, which can be mitigated by using a higher-octane fuel.
- Regularly towing heavy loads or operating in hot climates where higher octane can help maintain engine performance and prevent pre-ignition.
- Performance-oriented driving where the manufacturer advertises or implies a benefit from higher octane.
In many cases, higher octane will not produce dramatic gains in everyday driving, and the cost per mile is often higher. If your manual requires or recommends 89, or you notice knock on 87, switching to 89 is appropriate.
How to confirm your car’s needs
To avoid paying for the wrong fuel, use these steps to confirm the correct octane for your vehicle.
- Check the owner’s manual for the recommended octane rating (minimum vs. preferred).
- Look at the fuel door sticker, which often lists the required octane or fuel type.
- Consult your dealership or manufacturer if you’re unsure about high-performance variants or special engines.
- If you experience knocking on 87, try a higher octane and monitor the effect on engine behavior and performance.
Following official guidance ensures you’re using the appropriate fuel and helps protect engine longevity and performance.
Notes on cost, availability, and fuel quality
Beyond octane, fuels can differ in ethanol content and regional formulations. Most 87 and 89 octane fuels in the United States are E10 (about 10% ethanol). Availability varies by region, and premium grades (91–93 octane) are more common for high-performance engines. Price differences can be meaningful over the life of a vehicle, so balance the potential performance gains against the extra cost per gallon.
Summary
In short: for most vehicles, 87 octane is the sensible default and is typically sufficient. Use 89 or higher only if your manual calls for it or if you notice knocking with 87. When in doubt, consult the owner’s manual or your dealer, and consider the total cost of higher-octane fuel relative to any potential performance benefits.
Is it bad to put different gas in your car 87 instead of 89 gas in Nissan Kicks?
No. The recommended gas is what will get you the best performance and economy. Use a different one and it'll get worse. Every other effect is placebo.
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.
Can I use 89 instead of 87 on Reddit?
It's almost always okay to switch to a higher octane fuel, it won't hurt anything. Putting a lower octane fuel than required is what can hurt an engine. Mixing different octane ratings is not going to cause an issue either, unless you're putting a lower octane fuel in than required.
Does 89 octane burn slower?
No, 89 octane gasoline does not burn slower than lower octane fuel; both burn at the same rate and have the same energy content. The difference in octane is a measure of the fuel's resistance to "knock" or premature detonation. Higher octane fuel is more stable under compression, which is necessary for high-compression engines to prevent the fuel from igniting before the spark plug fires.
- Octane rating is for anti-knock: A higher octane rating means the fuel is more resistant to premature ignition from heat and pressure, not that it burns more slowly.
- Engine design is key: High-compression engines are designed to take advantage of higher octane fuel. In these engines, the higher octane prevents the fuel from auto-igniting under extreme pressure, allowing for more power.
- Standard engines don't need it: In most standard cars designed for regular (87 octane) gasoline, using a higher octane fuel like 89 or 91 offers no benefit and can even slightly decrease performance because the engine's timing is optimized for the slower burn rate of the lower octane fuel, say Quora users and Reddit users.
