Ever wonder why gas stations sell premium gas?
Every time I pull up to a pump, I see the three choices and the corresponding yellow labels with octane ratings. To be honest, up until a few weeks ago I really had no idea what the difference was between premium gas and regular gas – except for those yellow labels. And the price.
My thinking goes like this: “Why pay more for premium gas when regular gas seems to do the trick?”
All of this boils down to a single question that most of us have already answered in our heads: Is premium gas worth it?
I answered that question a long time ago: No. Why pay up to $0.55 more for gasoline that has no benefits other than higher octane?
Of course, my flat-out rejection of premium gasoline was largely built on a sort of cheapskate ignorance of what premium gas is, what octane measures and which situations call for premium gasoline.
Does premium gas increase fuel efficiency? Does it decrease engine wear? Will it turn my toddler-stained Hyundai SUV into a Formula 1 family car?
Well, it turns out that premium gas is actually a pretty fascinating liquid and the questions of whether or not your car needs it and why it would need premium gas is one that gets into how engines work and how octane levels affect engine performance.
Here’s the disclaimer: I’m going to explain all of this in easy-to-understand terms using the insight of experts who nerd out on engines and gasoline.
And, by the end of this article, you’ll know exactly why you should or shouldn’t put premium gas in your car.
What Is Premium Gas?
So, you drive up to the pump at your gas station and see three levels of gas: regular, mid-grade and premium.
We all pretty much know that premium has the highest octane – usually in the 90’s – and regular is the lowest and hovers around the mid-80’s.
That’s the easiest way to explain it: premium has a higher octane rating. And because of that, it costs more at the pump.
At the time of publishing, AAA noted that the average price of regular gas was $2.60 per gallon while premium was $3.12.
What Is Octane?
While the generally accepted definition of premium gas is pretty clear, what’s not clear is what octane is.
For that answer, I turned to Dr. John Nuszkowski, an associate professor at the University of North Florida. His research focuses on a lot of things, but what’s most pertinent to this discussion is his expertise in improving gas combustion.
I asked him what octane is and he gave a simple answer.
“A gasoline’s octane number is a rating of how likely a fuel will or will not self-ignite,” Nuszkowski said. “The higher the octane number, the less likely the fuel will self-ignite.”
The key phrase here is “self-ignite” because, frankly, that’s what all of this discussion about premium gas is about.
How an Engine Works: It’s All About Timing
You see, engines run on a series of small explosions of air and gas inside the engine. In theory, your car’s spark plugs are supposed to spark and ignite the air and gas at just the right time Those spark-plug induced explosions fire the pistons powering your engine.
It’s pretty much like those video games where you control a sprinter by pressing buttons at just the right time during their stride. If you press the button early, your runner slows down. If you time it right, you’ll fire the button right when the runner is in stride, making him or her run faster.
If your engine fires right, your car will run like it should. If your engine fires early, then bad things can happen, said O.J. Lopez, owner of Chicago’s Fluid MotorUnion.
“Imagine your engine’s piston moving very rapidly in one direction, and before it’s begun a change in direction, the force of the gas ignition hits it,” he said. “The speed of the engine and the force of the early ignition make for potentially catastrophic results: broken pistons, cracked rings, worn bearings and melted valves are all just some of the potential outcomes.”
Why does it fire early? That has to do with something called compression, which is basically pressure inside your engine.
And when you mix that pressure with gas and air, said Lauren Fix, a car expert known as The Car Coach, your gas could ignite prematurely instead of waiting for the spark plugs’ sparks.
Most cars can run fine on regular gasoline because they’re designed to run smoothly on gas with a mid-80’s octane level that withstands the engine’s compression.
In fact, Richard Reina, product training director at CARiD.com, says 70% of the cars on the road right now have compression levels that pair well with regular gasoline.
According to AAA, 16% of cars require premium gasoline and the other 14% use either mid-grade or alternative fuel sources.
Which Cars Need Premium Gasoline and What Are the Benefits?
There are two answers to the question of which cars use premium gasoline: the ones with higher compression and the high-performance ones.
The first answer is industry talk; the second is the one we’re probably all familiar with. They both describe the same type of car.
Vehicles designed for high performance – think higher speeds and horsepower – have a lot more compression going on in their engines.
While a mid-80’s octane gas might be able to handle the rigors of a minivan’s daily trips to school, stores, and other stuff, it just doesn’t have the guts to avoid early ignition in engines where there’s a lot of compression.
In simple terms, it will ignite before it’s supposed to because there’s just too much pressure and heat.
“Manufacturers use higher octane gasoline to make more power by pushing the engine a little harder,” Lopez said. “Because the fuel is more stable and less likely to ignite before it is commanded, more power can be made safely.”
Most of the cars that require premium fuel are either luxury brands or sports cars. Here’s a list of a few cars that require premium gas, via BestRide.com:
- 49 Audis, including the A4 and S4
- 85 BMWs, including the 228i Couple and the 3 series
- Scion FR-S
- Nissan Juke NISMO RS
- Subaru BRZ
- Volkswagen Passat V6 SEL Premium
Most of these cars are priced at or above the average price of a new card, BestRide pointed out.
If you’re unsure of which grade of gasoline your car needs, Lauren Fix says it’s always best to follow what the manufacturer recommends for your car.
And one more thing: Some manufacturers will require high-octane gas for a certain car and some will recommend it.
The difference here, said Dr. Chris Kabana, lead additives product engineer at Gold Eagle Company, is that most “recommended” cars can run on regular without imminent danger to the engine, whereas cars that are required to use high-octane fuel will most likely face some serious issues if you fill up with regular all the time.
Can You Use Premium Gasoline in Cars That Run on Regular?
You’ve probably gathered by now that high-octane gas has the fortitude to withstand the insane amount of pressure that certain high-performance cars exert on their engine.
While regular gas’ low octane levels won’t work in the performance cars because it will most likely create timing issues and extra wear or damage, premium gas will work well in cars designed to take regular.
“The use of premium in a ‘regular performance’ engine does not provide a real, discernible value,” said Dr. Chris Kabana, lead additives product engineer at Gold Eagle Company. “Premium gasoline is absolutely worth it for vehicles that require it. Otherwise, simply stick with regular gasoline.”
In other words, putting premium gasoline in a car that only needs regular is like wearing a parka on a summer day – all you really need is a t-shirt.
Consumer Reports and AAA: You’re Wasting Money on Premium Fuel
There’s even some question about whether or not premium gas can help cars whose manufacturers recommend premium gas, but don’t require it.
A 2016 study from Consumer Reports highlighted the effects of premium fuel on two cars: a 2015 Acura TLX and a 2016 Nissan Maxima.
“Both sedans achieved the same fuel economy when tested with regular gas as with premium,” the report concluded. “During this testing, the cars felt and sounded the same; we did not experience any engine pinging or knocking noise in either car when using regular fuel.”
Here’s the catch, though: Consumer Reports ran the cars on one full tank of regular gas. While the cars may have shown no signs of poor performance on one tank of gas, it would be tough to conclude that they wouldn’t exhibit poor performance if you used regular gas all the time.
Consumer Reports’ conclusion about using premium gas in cars that recommend it: Don’t bother.
But yet, according to a Sept. 2016 press release from AAA, more than 16 million of us do bother every year, to the tune of more than $2 billion spent on premium fuel. Why do we keep throwing away money on premium fuel?
AAA Managing Director of Automotive Engineering and Repair John Nielsen said consumers are a little confused about what premium gas does.
“Drivers see the ‘premium’ name at the pump and may assume the fuel is better for their vehicle,” Nielsen said in the press release. “AAA cautions drivers that premium gasoline is higher octane, not higher quality, and urges drivers to follow the owner’s manual recommendations for their vehicle’s fuel.”
This is an interesting point: premium fuel isn’t necessarily higher quality, which brings me to my final point.
If You Want Better Quality Gas, Skip Premium and Use Top-Tier
Unless your car’s manufacturer says you must use premium gasoline, the research says that you’re far better off saving your money and using regular gas. In fact, 84% of cars on the road today don’t need premium gas to run well.
If it’s better quality gas you’re looking for, then the experts are quite clear on the fact that gasoline certified by the TOP TIER program is better for your car than non-TOP TIER gas.
Why? Because TOP TIER gas includes vital detergents that keep your engine burning cleaner and stave off unnecessary wear.
Nuszkowski said that an engine will experience 1.5 billion little explosions over 10 years as spark plugs ignite your air-fuel mixture. Any small difference in the amount of detergent in your gas could have a very real effect on your engine.
Thankfully, TOP TIER isn’t going to drain your wallet like premium would. In fact, our research showed that TOP TIER gas costs, on average, only $0.03 more per gallon.
Some of the gas stations who sell TOP TIER fuel include BP, Phillips 66, Texaco, Valero, and CITGO. Costco is the only warehouse club who sells TOP TIER.
If you want to learn more about TOP TIER gasoline, check out the TOP TIER gas guide we wrote. In the article, we talk about what TOP TIER gas is, why it helps your engine and where you can buy it.