What Happens if I Accidentally Put 89 Gas Instead of 87?

Patrick Oziegbe
Updated On:

You might be wondering what happens if you accidentally put 89 octane gas in your car instead of the recommended 87.

Don’t worry, your car will be just fine! In fact, using a higher octane fuel won’t cause any harm to your engine.

However, it’s important to remember that using a higher octane fuel won’t provide any noticeable benefits in performance or fuel efficiency.

So, while it won’t harm your car, it may not be an ideal choice for your wallet.

What happens if I accidentally put 89 gas in my car instead of 87?

Understanding Octane Ratings

When it comes to gasoline, understanding the octane ratings can help you make informed decisions for your car.

This friendly guide will explain the differences between 87, 89, and 91 octane gasoline, so you know what to expect when you fill up your tank.

87 Octane

87 octane is considered regular gasoline, it has a lower octane rating, which means it is less resistant to pre-detonation, or engine knocking, than other higher-rated fuels.

Typically, cars with lower-performance engines will use 87 octane gasoline. Your car’s manual will mention if 87 octane is suitable for your car. It is economical and widely available at gas stations.

89 Octane

89 octane, also known as mid-grade gasoline, lies between regular and premium fuels in terms of its resistance to engine knocking.

Some cars might perform better with 89 octane, especially if they have engines that could benefit from a slightly higher octane rating.

If you accidentally put 89 octane instead of 87, don’t worry, as stated by this Lifehacker piece, your car will be perfectly fine. However, using 89 octane instead of 87 might not provide any significant improvements in performance or fuel efficiency.

91 Octane

91 octane, also known as premium gasoline, offers the highest resistance to pre-detonation and is designed for high-performance cars with high compression engines.

Using 91 octane in a car that requires premium fuel can help prevent engine knocking and provide better efficiency.

Keep in mind that if your car’s manual specifies the use of premium gasoline, it’s essential to follow those guidelines to avoid damaging your engine.

In summary, understanding octane ratings can help you make the right choice for your car, especially popular SUVs like good RAV4 cars.

Always refer to your car’s manual to know which octane rating is recommended, and remember that using a higher octane rating than specified won’t harm your car, but it may not provide any noticeable benefits either.

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Effects of Using Higher-Octane Gas on Your Vehicle


When you accidentally put 89 gas in your car instead of 87, you may notice a slight improvement in performance.

Higher octane fuels can withstand more compression before detonating, making your engine run more efficiently and produce less emissions.

Fuel Economy

Although it’s not a significant difference, using a higher-octane fuel might lead to a decrease in fuel economy. However, this varies depending on the engine and vehicle type.

Combustion Process

The combustion process could be affected by the higher octane fuel, as it can withstand more compression before igniting. This means your engine may experience less knocking and smoother operation.

Remember, using 89 gas instead of 87 won’t severely harm your vehicle, but make sure to consult a trusted mechanic if you’re concerned about any potential issues.

Can You Mix 87 and 89 Gas?

Yes, you can mix 87 and 89 gas in your car. Doing so will not cause any immediate harm to your engine. In fact, using a higher octane rating like 89 instead of 87 won’t hurt anything except maybe your wallet.

Remember to check your car manual for the recommended octane level. If you ever mix up gas grades accidentally, don’t worry – just keep an eye (and ear) out for any persistent engine knocking as it could indicate potential issues.

Potential Issues with Accidentally Using 89 Gas Instead of 87

Engine Knocking

Although it is unlikely, using 89 octane gas instead of 87 might cause engine knocking in some cases. Engine knocking is when the fuel in your engine combusts at the wrong time. However, modern cars have advanced systems that usually prevent this issue.

Warranty Implications

In general, putting 89 gas in your car instead of 87 should not have any warranty implications. Most car manufacturers allow for a small variation in fuel octane levels. Just be sure to use the recommended octane level next time.

Fuel System Problems

Using 89 gasoline shouldn’t cause any fuel system problems in your car. As long as you continue to maintain your vehicle, its fuel efficiency (MPG) should remain consistent.

How to React When You Realize You’ve Used the Wrong Gas

Don’t Panic

If you accidentally put 89 gas in your car instead of 87, it’s not the end of the world. In most cases, your vehicle will continue to run without any major issues.

Just relax, knowing that your engine typically won’t suffer any long-term damage from this minor mistake.

Consult Your Vehicle’s Manufacturer

To be on the safe side, it’s a good idea to check your vehicle’s owner manual or contact the manufacturer for advice. They’ll provide guidance on whether further action is needed, or if your car can simply burn off the slightly different fuel.

Monitor Your Vehicle’s Performance

After using the wrong gas, keep an eye on your car’s performance. If you notice any unusual noises, loss of power, or other irregularities, it might be worth consulting a mechanic.

However, most of the time, you’ll find that your vehicle continues to run smoothly with 89 gas instead of the 87 regular fuel it’s designed for.

Preventing Accidental Use of the Wrong Octane

Gas Station Tips

To avoid using the wrong octane, double-check the gas pump label before filling up. Remember to choose the regular gas (87 octane) for your vehicle and avoid confusing it with premium gas.

Staying Informed

Always refer to your owner’s manual for the recommended octane rating. By staying informed, you’ll prevent any accidental mix-ups at the gas station and protect your car’s engine.

Selecting the Best Gas for Your Vehicle

Luxury Cars vs Regular Cars

When choosing fuel for your car, it is important to consider the type of vehicle. Luxury cars like BMW and Mercedes often require premium gas (as per cars.com), while regular cars like the Honda Civic work well with 87 octane fuel.

Turbocharged Engines

For turbocharged engines, using a higher octane fuel like 89 can prevent engine knocking and improve performance. If you accidentally put 89 gas in your car instead of 87, it is usually safe and should not cause any damage.

High-Performance Cars

High-performance cars typically need higher octane fuels to maintain optimal performance. Using a lower octane fuel can potentially harm the engine, so always check your owner’s manual for the recommended fuel grade.

Frequently Asked Questions

Can using 89 gas instead of 87 harm my engine?

No, using 89 gas instead of 87 won’t harm your engine. In fact, most cars recommend using standard grade 87 or 89. So, don’t worry if you accidentally put 89 instead of 87, as your engine will be perfectly fine.

Is it safe to drive after accidentally putting 89 instead of 87?

Yes, it is safe to drive after accidentally putting 89 instead of 87. The difference in octane ratings won’t have a significant impact on your engine or performance. Just continue driving and filling your tank with the recommended gasoline in the future.

Do I need to drain the tank if I put 89 instead of 87?

No, you don’t need to drain the tank. Since using a higher octane blend doesn’t cause any damage, you can simply continue driving your car with the 89-octane gasoline in the tank.

Can I mix 89 and 87 gas if I made a mistake?

Yes, you can mix 89 and 87 gas. If you happen to make a mistake and use 89 instead of 87, your engine will still perform well with the mixed fuel. Combining the two octane levels won’t cause any harm to your car.

Will fuel efficiency be affected if I used 89 instead of 87?

No, your fuel efficiency should not be significantly affected by using 89 instead of 87. The difference in octane ratings mainly affects the way fuel burns in your engine, but it won’t have a noticeable impact on your car’s fuel efficiency.

However, always consult your car’s owner manual for the most accurate information regarding recommended fuel specifications.


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