Premium vs Regular Gas: Which One Do You Really Need?

The premium vs regular gas question can be a confusing one. Although the fuel pump at your local station might seem to present you with a simple question of good/better/best, when looking at the branding and pricing of the gasoline you are offered, in reality the answer is a little more complex. You’ve got to throw away everything that consumer training has taught you via advertising and pricing structure to understand whether you really need to pay more for premium fuel.

Gasoline Basics
Adding fuel to an automobile.

At the heart of the premium vs regular gas conundrum is the concept of “octane.” Every type of fuel sold in the United States features an octane rating, typically ranging from 87 octane for regular gas all the way up to 91 or 93 for premium (with 89 octane sitting somewhere in the middle). A common mistake is to assume that higher octane fuels are somehow more “powerful” than lower octane fuels — a misconception that is encouraged by the marketing departments of major oil companies across the country.

In fact, octane is a shorthand measure for how well a gasoline’s formulation resists detonation inside your motor. Every gas-powered automotive engine compresses a mixture of fuel and air and then ignites it with a spark plug to generate power. It’s vital that this mixture resist ignition until the spark plug fires, with higher octane fuels able to do this better than lower octane fuels. If fuel and air ignite prior to the spark plug doing its job, it creates a condition called “knock,” which can damage a motor and reduce power.

How to Know If You Need Premium

The easiest way to decide whether you need premium vs regular gas is to simply read you car’s manual or check out the label on the inside of the fuel filler door: each of these will lay out the specific requirements of your car’s engine. In general, if you have a vehicle with a high compression engine — typically found in a performance automobile or a turbocharged or supercharged motor — then you will need a higher octane fuel that can resist the ignition pressures found inside your car’s cylinders.

Putting premium gas in a car that doesn’t actually need it will give you absolutely no performance or efficiency benefits. Unless it’s specifically programmed to do so, the computer that controls your vehicle’s motor simply can’t take advantage of the improved knock resistance of high octane fuel by altering the ignition cycle.

Premium gas won’t burn cleaner or even offer you more power in an engine that’s tuned for regular — it will just drain your wallet that much faster.

Check out all the Fuel & Emission System parts available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on gas types, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photo courtesy of Morgue File

about author

Benjamin Hunting

Having been bitten by the car bug at a young age, I spent my formative years surrounded by Studebakers at car shows across Quebec and the northeastern United States. Over ten years of racing, restoring, and obsessing over automobiles lead me to balance science writing and automotive journalism full time.  I currently contribute as an editor to several online and print automotive publications, and I also write and consult for the pharmaceutical and medical device industry.

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