With gas prices fluctuating wildly these days, drivers are looking for ways to save money at the pump. One question that often comes up is whether using a lower octane gasoline, such as 89 octane, can help cut fuel costs without sacrificing performance or fuel economy.
What is octane and why does it matter?
Octane is a measure of a fuel’s resistance to engine knock or premature combustion. Most regular gasoline sold in the U.S. has an octane rating of 87. Premium gasoline has an octane rating of 91-93. Midgrade 89 octane falls in between.
Higher octane fuels have higher resistance to knock. This allows them to withstand the high temperatures and pressures inside combustion chambers without igniting too soon. Premature ignition can reduce power and fuel economy while potentially damaging the engine over time.
Engines are designed to run on a certain octane fuel. Using gasoline with too low of an octane rating can cause persistent knocking, especially under load or acceleration. On the other hand, using a higher octane fuel than recommended is unlikely to provide any benefit.
Do most cars require premium 91+ octane gas?
Despite what you might hear, most modern car engines are designed to run just fine on regular 87 octane gasoline. Premium higher octane fuel is only required for certain models:
- High-performance sports cars or muscle cars
- Luxury vehicles
- Cars with turbocharged or supercharged engines
- Some newer large trucks designed for heavy loads or towing
For a typical family sedan or compact car driven under normal conditions, 87 octane gasoline is sufficient. The owner’s manual will state the recommended fuel grade.
What are the benefits of using midgrade 89 octane gas?
Midgrade 89 octane gas sits right between regular and premium. Filling up with midgrade offers some key advantages:
- Prevent knock in borderline engines – Some engines are designed to run on regular gas, but may experience occasional knocking or pinging under load. 89 octane can help eliminate this issue.
- Added protection for high mileage engines – Older engines with more wear may benefit from midgrade to prevent pre-ignition.
- Better performance for towing or hauling – The extra octane helps reduce knock when the engine is working hard under heavy loads.
- Peace of mind – For those who aren’t sure if their car needs premium, midgrade splits the difference.
For most drivers though, the difference between 87 and 89 octane gas in standard everyday driving is negligible. But midgrade does offer an extra margin of protection when pushing the engine into higher RPMs or operating ranges.
Is 89 octane gas bad for your engine?
There is no harm in using a gasoline with a higher octane rating than your owner’s manual recommends. The key thing is to avoid gasoline with too low of an octane.
Since most regular passenger vehicles only require 87 octane, filling up with 89 octane gas likely won’t provide any benefit outside of very specific driving scenarios. The engine isn’t designed to take advantage of the extra knock resistance.
But that doesn’t mean 89 octane gasoline will cause problems or is “bad” for your car. The higher octane provides an added buffer against abnormal combustion. If anything, midgrade gasoline is safer for the majority of car engines, even if owners are paying extra for no practical gain.
Does 89 octane gas improve fuel economy?
Despite some claims, using a higher octane gasoline than the owner’s manual recommends does not improve fuel economy. Tests have shown no meaningful difference in MPG between 87 and 89 or even 93 octane gas in regular cars.
The octane rating itself has no bearing on energy content. Gasoline contains the same number of BTUs per gallon regardless of octane. Two gasolines with a 10 octane rating difference have a negligible variance in energy density.
Since a typical car engine isn’t built to take advantage of higher octane fuel, it cannot translate the increased knock resistance into better mileage. You’re essentially paying more for 89 octane gasoline without any tangible benefit.
When does it make sense to use 89 octane gas?
Here are some of the main situations where drivers may benefit from using 89 octane gasoline:
- Turbocharged or supercharged engines – The added pressure increases knock risk, making midgrade or premium advisable.
- Performance sports cars – High compression engines need higher octane to prevent pre-ignition when revving high RPMs.
- Trucks using max towing or payload – Midgrade can help reduce knock with heavy loads straining the engine.
- Older engines – Wear and carbon buildup over 100k+ miles increases knock risk that 89 octane can help control.
- When engine knocking is heard – Persistent knock indicates the need for a higher octane fuel.
- Hot weather driving – Very high temperatures increase pre-ignition risk load, making midgrade a reasonable precaution.
For most everyday drivers though, 89 octane gasoline provides no discernible advantage in normal operating conditions. While it certainly does no harm, the extra cost per gallon is unlikely to be justified.
How much more does 89 octane gas cost?
The price difference between regular 87 octane and midgrade 89 octane gasoline can vary substantially based on location, season, and broader fuel cost trends. But in general, expect to pay a premium of:
- 10 to 15 cents more per gallon for 89 vs 87 octane at the lower end
- 20 to 30 cents more per gallon for 89 vs 87 octane on the higher end
Here’s a look at average 89 vs 87 octane gas prices nationally over the past few years:
| Year | 89 Octane Gas Price | 87 Octane Gas Price | Price Difference |
|---|---|---|---|
| 2022 | $3.64/gallon | $3.41/gallon | 23 cents |
| 2021 | $3.02/gallon | $2.89/gallon | 13 cents |
| 2020 | $2.16/gallon | $2.03/gallon | 13 cents |
Based on historical prices, drivers have paid an average premium of 15-20 cents per gallon when opting for 89 octane gasoline over regular 87 octane fuel.
Is it worth paying extra for 89 octane gas?
Whether it makes sense to pay up for 89 octane comes down to your specific vehicle and use case. The cost vs benefit calculation depends on:
- Does your engine require or recommend premium fuel? What does the manual say?
- Do you regularly carry heavy loads, tow trailers, or push the engine into high RPMs?
- Is it an older engine with significant mileage or observable pre-ignition?
- Are you travelling/driving in consistently hot conditions?
For most everyday drivers covering normal miles in a properly maintained engine, 89 octane gas provides minimal benefit over regular 87 octane fuel, if any at all. The 10 to 30 cent per gallon premium price is hard to justify.
However, 89 octane makes sense for drivers who need that extra knock protection when frequently operating in high demand scenarios. It also gives peace of mind to those who aren’t sure if their engine requires premium, providing a “better safe than sorry” middle ground.
Conclusion
While 89 octane gasoline does no harm and adds a level of engine protection, for the vast majority of drivers, regular 87 octane gas is perfectly sufficient. Use the octane rating recommended in your owner’s manual for optimal efficiency and performance.
Midgrade 89 octane fuel is best reserved for scenarios that increase pre-ignition risk – like towing heavy trailers, carrying big loads, driving aggressively, or operating in extreme heat. For normal everyday transportation, drivers gain little benefit from paying a 10-30 cent per gallon premium for 89 octane fuel versus regular 87 octane gas.
