Premium Gas…Should I Be Paying For it?
Every time you pull up to a service station, you have a decision to make: what level of octane should you choose to put in your gas tank? For many of us, we don’t give this a second thought…but maybe we should.
What is Octane Anyway?
If you’ve ever wondered what those three numbers on the fuel pump mean, 87, 89, and 91 or some similar variation, you’re not alone. You may also hear these octane levels referred to as regular (87), mid-grade (89) and premium (91 to 93).
Octane ratings indicate the performance capability of the fuel. Gasoline engines rely on the ignition of air and fuel compressed together as a mixture.
Technically, the octane rating of gasoline identifies how much this air-fuel mixture can be compressed before it will spontaneously ignite and allow the engine to function. The octane rating is the measure of a fuel's ability to resist "knocking" or "pinging" during combustion (when the air/fuel mixture ignites properly in the engine).
In the old days, engines could not adjust to fuels with varying octane ratings. If a car used the wrong fuel, the engine would knock or "ping" because the gas ignited prematurely. And over time, this would damage the internal engine components.
But today, advanced engine control technology can compensate for varying levels of octane and provide drivers more flexibility in the grade of fuels that they can safely use.
The sale of low octane fuel (87) was originally allowed in high-elevation regions, where the barometric pressure is lower. This was permitted because this gasoline was cheaper and because most carbureted engines tolerated it fairly well. But this is no longer true for modern gasoline engines. Today, very few cars use the lowest level of octane fuel. And few, if any manufacturers recommend it.
Actually, every state has the ability to set its own approved octane levels. For example, due to emission regulations, the 93 octane level is not available in some states, such as California.
All that being said, the real question is “does it really matter what type of gas you put in your car, truck or SUV?” The answer is yes….and no.
According to the numerous studies conducted by the Federal Trade Commission (FTC), “Unless it’s recommended by your owner’s manual, don’t spend the money on high octane gas. In most cases, there’s no benefit. Higher octane helps only if you have problems with your engine knocking.”
The Automobile Club of America (AAA) agreed with the FTC stating that “U.S. Drivers Waste $2.1 Billion Annually on Premium Gasoline” and they have a landmark study to back up this claim.
• AAA used an independent third party testing lab to determine how octane affects performance
• Final results of the AAA study found no benefit in high octane fuel in cars that suggest using premium fuel
• The AAA stated that “using a higher octane fuel than a vehicle’s owner’s manual specifies no increase in fuel economy, horsepower or a reduction in emissions. When premium fuel is merely recommended, there is no reason to use it instead of regular”
And for additional reassurance, the experts at Consumer Reports confirmed these findings when they stated, “Vehicles that recommended premium did not increase acceleration or fuel economy compared with regular gasoline.”
As mentioned, premium gas is defined as fuel that has a higher octane rating of 90 or higher, usually 91 (or 93 if allowed in the particular state). The central theme in choosing the proper grade of fuel is distinguishing between what is recommended and what is required.
Since 1960, Edmunds has been a leader in automotive information. Their professional advice for drivers is to understand whether premium gasoline is merely suggested for their car or if it is necessary.
For cars with engines that require premium fuel, it’s best to stick to the higher grade. In these cases, lower octane can result in elevated temperatures and possible knocking, both of which can adversely affect the engine's health in the long run.
According to experienced mechanic, Robert Keirstead, owner of 26th Street Auto Center, one of the busiest independent repair shops in Los Angeles, his busy automotive complex has seen owners complaining about these and other problems, often caused by using the wrong gasoline/octane level.
“A vehicle that requires premium, but is actually fueled with a lower grade on a consistent basis often results in a large amount of carbon build up in the throttle body and intake,” Keirstead states. The problems from using the lesser octane may not arise immediately, but eventually, there will be serious issues and possible damage.” If the problem is not addressed, expect the check engine light to come on, usually from a misfire symptom.
Edmunds goes on to explain that if your owner’s manual recommends premium fuel and you choose regular octane levels, you should not experience any problems and you will likely not damage your engine.
Since regular unleaded gas typically costs about 15 to 20 cents less per gallon than premium, the savings can lead up to as much as $4 per fill-up, which is over $200 annually if you fill up every week.
But buyer beware! If the owner’s manual says “(mileage) ratings were achieved using the required premium unleaded gasoline with an octane rating of 91 or higher,” then the driver should use this high level to maximize performance.
For example, if you purchased an automobile because you crave the high performance and MPG it delivers, it’s essential to follow the guidelines set forth by the manufacturer. After all, the octane level listed in the manual is the octane level they used to calculate the performance, durability and fuel economy.
Therefore, when you purchase a car, such as a BMW, and the information in the owner’s manual states that premium fuel is required, this is done to allow the driver to obtain the same horsepower and performance that the manufacturer presents in their data. However, in some instances, cars that require premium can run on regular, albeit with lower results than advertised. And many tests show that continued use of regular-grade fuel in a vehicle that requires premium grade may cause ignition issues, adversely affect power, and reduce the fuel economy.
In other words, you may not realize your car’s performance or fuel economy potential without using top tier gasoline when the vehicle’s manufacturer requires 91/93 octane gasoline.
Horsepower and Octane Levels
When purchasing an automobile, some salespeople may indicate that a vehicle’s power fuel economy may increase up to five percent if high octane gasoline is used, even if the owner’s manual does not state it.
Keirstead of 26th Street Auto Center again offers some sage advice. “It is entirely possible that you could see up to five percent more horsepower using premium fuel versus regular in a modern car,” Keirstead says. “Today’s vehicles are like computers on wheels and their complicated systems utilize advanced technology, such as a knock sensor. This sophisticated sensor can effectively decipher what grade of gas you are using by how well the car is combusting the fuel in the engine and how smooth it is running. It is feasible that the higher the octane, the higher the horsepower and the potential of increasing fuel economy.”
However, Keirstead warns that “fuel economy is very subjective based on how you drive your car and that better horsepower does not necessarily equate to better fuel mileage.”
What About Your Specific Car?
There are a wide variety of car models, both old and new, both compact and luxury trims that have high-compression engines and electronic controls which are designed to benefit from the greater power output and improved fuel economy of high octane fuel.
Review this comprehensive list from Edmunds.com to understand if your car requires premium gasoline. You may be surprised not all on this list are new or lavish vehicles, although some luxury brands, such as BMW and Mercedes, have high-compression engines that require the use of premium gas to prevent the engine from knocking. If your car does require premium, then constantly using lower regular octane levels will result in damage to your car.
Quite simply, if your car, truck or SUV requires top-tier fuel, then using regular octane level gasoline will lead to damage. If you decide to save money and use regular gasoline when top-tier fuel is required, you’ll likely pay more to fix the engine later on.
The Bottom Line
It is important to remember that premium gasoline is higher octane, not higher quality. According to AAA, 70 percent of Americans drive cars that need only regular gas, while 16 percent require premium and the remaining 14 percent need mid-grade (regular) gas or have an alternative power source like electric batteries.
Experts agree that using higher-octane gasoline in an engine that only recommends, not requires, premium fuel is wasting money, something most of us cannot afford.
Don’t fall victim to the urban myth that fueling up with the highest-grade octane gas is a good idea if your car is designed to run on the regular stuff. Keep those hard-earned dollars in your pocket and avoid being one of the 16.5 million motorists that fills up unnecessarily with premium gas.