Fuel Octane: Choosing the Right Gasoline

What is octane rating?

Octane rating is the measure of a fuel’s ability to resist knocking, caused by the air and fuel mixture released prematurely in the engine, during combustion.

 

What fuel should I use in my vehicle?

Check your owner’s manual for the octane rating required for your vehicle by the manufacturer. You should choose that fuel when at the gas pump. Most gasoline vehicles run on 87 octane, but others are designed to run on higher octane fuel.

 

Why do some manufacturers require higher octane gasoline?

Engines that use higher compression ratio and/or use turbocharging to force more air into the engine, require higher octane fuel. Higher cylinder pressure allows the engine to make more power from the given air/fuel ratio. High octane fuel is used in order to prevent pre-detonation in the cylinder (spark knock). Improved performance and fuel economy will result in these engines.

 

What happens if I use a lower/higher octane fuel than required for my vehicle?

Using a lower grade can cause the engine to perform (power and fuel economy) poorly and can damage the engine and emissions control system with time. It can also void your vehicle’s warranty.

Using a higher grade may improve performance and mileage, but depends on the vehicle and conditions. If towing a trailer or heavy load in hot weather, you may see a small percent improvement; however, under normal driving conditions, you may see little to no difference.

 

Why is higher octane fuel more expensive? Is it worth the premium?

Generally, the fuel components to produce premium grade are more expensive. If your vehicle requires midgrade or premium fuel, it’s absolutely worth the extra cost. If your owner’s manual says your vehicle will run better on higher octane fuel but doesn’t require it, it’s totally up to you. The higher cost of premium fuel offset most fuel economy savings. However, decreasing emissions and petroleum usage (even a small percentage) may be more important than cost to you.

 

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Dowell Automotive

For those who live in the Greater Lafayette area, Dowell Automotive would be happy to inspect and advise you on which fuel grade is right for your desired performance and fuel economy.

To make an appointment give us a call at 765-477-0333 or visit us.