Paying extra for premium gas? You should probably stop

You love your car. You want to treat it well. You definitely don’t want to do anything that will damage it. That’s why you filled it with premium gasoline all these years. But with prices over $7 a gallon, you started to wonder: does my car really need the good stuff? Can I just switch to normal? Or should I compromise and buy mid-range?

Answers: Probably no, probably yes, and almost certainly not.

Confused? Don’t worry, you’re in good company.

Many years of research at the Los Angeles Fuels Laboratory of the American Automobile Assn. showed that if your car requires a premium, you should continue to use the premium and absorb the cost. But thanks to a mix of clever marketing and quirky consumer psychology, some 16.5 million American drivers are filling up their premium cars when normal would run just as well, according to AAA.

Do you think you are one of them? Check your owner’s manual, advises Doug Shupe, program manager at the Automobile Club of Southern California and AAA. And pay close attention to the language. “Unless your vehicle manufacturer indicates premium fuel is required — not recommended, but required — we found no benefit to using premium fuel,” Shupe said.

If it says “recommended”, you can ignore the recommendation and pocket the 30 to 50 cents per gallon you’ll save. Spending more doesn’t buy any advantage in horsepower, fuel economy or emissions, Shupe said.

Depending on the distance traveled, the switch can save you several hundred dollars a year. With the average price of a gallon of regular fuel now over $6 in California, that’s money that could go to food or rent.

What does “premium” mean? This grade of gasoline contains an extra dose of hydrocarbon molecules called octane. In a high-compression engine, high pressure can compress the air-fuel mixture so tight and hot that some of the fuel burns off before it fails. This leads to uneven explosive forces, which can cause engine parts to vibrate unnecessarily. The extra octane helps the fuel burn more evenly.

In California, premium gas is labeled 91 octane, midgrade is 89, and regular is 87. All are unleaded.

AAA’s octane test results are widely accepted. So why would a car manufacturer recommend a premium when it is not necessary? One reason may be the belief of many customers that premium, required or not, improves engine performance.

For a manufacturer looking to back up the high price of a luxury car with equally high performance claims, the association might not hurt. In fact, some high-end models like Audi and BMW have a sensor that can tell if the gasoline is premium or regular, according to Jil McIntosh at Autotrader, and adjust the engine accordingly.

The AAA lab has not tested the benefits or harms of mid-grade fuel. This could be because there aren’t many benefits to speak of, except for gas industry profit margins. (The exception is older cars with engine knock, which can potentially benefit from mid-grade gas.)

The choice of medium is an artifact of the time when unleaded gasoline began to appear as an alternative to gasoline containing lead. Gas stations needed three pumps to sell regular lead, regular unleaded and super unleaded. After the phase-out of leaded gasoline starting in the 1990s, the intermediate level was a means of using the third pump.

Mid-grade represents a tiny fraction of retail gasoline sales. According to the US Energy Information Administration, about 88% of the gas sold in the US is regular, 11% premium and the rest mid-grade.

If mid-tier customers are trading lower than normal, whether they need it or not, this pump offers bigger profit margins. When premium customers trade, profit margins are squeezed.

One thing all gasoline buyers should look for if they’re looking for performance and longer engine life, according to Shupe: an indication that a gas station is selling “premium” fuel. There will often be a label on the pump. Most major brands do; many smaller brands do this too. Any grade of gasoline – regular, intermediate, premium – can be top tier.

This gasoline is treated with additives that reduce carbon buildup and is tested by an independent group to verify the formulation. Tests show that such fuel improves performance and extends engine life. Brand names such as Chevron’s Techron and Shell’s V-Power are top notch, for example, although they aren’t always referred to that way.

These fuels cost more than gasoline at discount stations that don’t sell Top Tier gasoline, but the AAA suggests the extra pennies are worth it.

High gasoline prices continue at a 76 station off Los Feliz Boulevard on May 31, 2022 in Los Angeles.

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