When you pull into a gas station, you'll usually notice three grades of unleaded gasoline: regular, mid-grade, and premium.

Each type of fuel has a corresponding octane rating, with regular, mid-grade, and premium at 87, 89, and 91 or 93, respectively.

Each grade has a corresponding price. It may seem like premium, being the most expensive, is the best fuel for your car. But that isn't always the case. 

The octane number specifies the gasoline's ability to resist pre-ignition of the air and fuel in the combustion chamber. Automakers design engines to fire at exact times. If that happens too soon, engine knocking or pinging sounds occur. Besides causing unpleasant sounds, pinging and knocking may cause severe damage to the pistons, cylinders, and consequently, the entire engine.

Sports cars with high-performance engines and vehicles with turbochargers usually feature higher compression ratios and need fuel that resists pre-ignition, which means they require premium gasoline with a high octane rating. 

However, for regular passenger vehicles, there's no noticeable advantage to using premium gas. 87 octane will serve you just fine. But if your engine requires higher octane gas and you fill up at the gas pump with lower-grade gasoline, it could result in pinging and knocking, pre-ignition, and engine damage. 

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Besides filling up with the correct octane of gasoline, you can also try Top Tier gasoline, which is certified to contain higher detergents levels than the EPA requires.

Cleaning detergents help keep the fuel system clean and working optimally. Detergents also rinse away valve deposits for a smooth-running engine. 

A group of automakers, including Volkswagen, Honda, Audi, BMW, Toyota, and General Motors, created the Top Tier standard in 2004.  

According to a AAA study that compared Top Tier gasoline to fuels with lower levels of detergents, Top Tier gasoline can reduce engine deposits by 19 times. The AAA study also found that using non-Top Tier fuel can reduce fuel economy by up to 4%. 

Premium gasoline varies by state and manufacturer

Depending upon which state you reside in, premium gasoline carries an octane rating of 91 or 93. Both qualify as premium fuel, and if your vehicle requires high-octane fuel, either will work equally as well.

Different oil companies also have their own unique formulations of premium gasoline that contain specialized additive packages.

ExxonMobil makes Synergy Supreme+ with extra detergents for cleaner fuel injectors and increased gas mileage. Synergy Supreme+ is so effective that it can remove deposits left behind by lower-quality fuels. Chevron’s Techron additive helps protect engine parts, reduce emissions, and clear away deposits, too.

Should you use premium fuel?

Because premium gasoline has a higher octane rating and costs more, it might seem like a superior option compared to regular and mid-grade.

But if your make and model doesn't require premium gasoline, there's no benefit to using it.

The EPA mandates all gasoline grades contain a minimum level of engine-cleaning detergents to keep your engine in excellent condition. These detergents prevent the formation of deposits and help clean away old ones. 

However, if you drive a high-performance car or one with a turbocharger, and your manufacturer requires the use of premium fuel, it's essential to use it when you fill up the tank.

Manufacturers design engines with specific levels of performance and economy in mind. It’s what they’re passionate about. They recommend particular fuel grades based on what their engines need to function as they were designed to. Using the specified type of gasoline ensures optimal performance and fuel economy and helps your engine provide steady, reliable transportation for as long as possible.

If your engine requires premium and you fill up the tank with the wrong fuel, it might cause noises like pings and knocks or more serious mechanical issues.

And if you have a vehicle that only requires regular fuel, filling up with higher octane fuel, you're simply spending extra money with no added benefit. Instead, you can make your car work and look great by investing in oil changes, new tires, and a DIY wash and wax.

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