Premium vs. Regular Gas Explained

Premium vs. Regular Gas Explained

When you pull into a gas station, you see two or three different grades of gas with octane ratings ranging from 87 to 93. The lowest octane rating is regular, and the top octane rating is premium. If there’s one in the middle, it’s mid-grade. 

Regular gas is always the cheapest grade, and the premium is always the most expensive. It would seem like the more expensive product with the higher numerical rating would be better for your car, right? 

After all, no matter the product, something that’s usually more expensive and carries a superior rating seems like it will perform better.

But that isn’t the case when comparing premium and regular gas. Each has a specific purpose, and for a car to run its best, it needs to be using the grade recommended by the manufacturer. 

What do octane ratings mean, and how do they affect your car? Let’s look at premium and regular gas and see why higher octane and a higher price don’t always mean superior performance.

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Octane ratings: what do they mean?

Octane rating is the measure of a grade of gasoline’s ability to prevent pre-ignition of the air-fuel mixture. By design, internal combustion engines fire at a very specific time, and if this happens too early, the engine will begin to make pinging or knocking sounds. Aside from the sounds, pinging and knocking can cause severe damage to the pistons,cylinder linings, and, in turn, the entire engine.

Premium gasoline resists pre-ignition in high-performance engines that have high compression ratios or turbochargers. Regular gasoline is fine for typical engines, but if regular gas is used when premium is required, it may cause pre-ignition, knocking, and pinging, as well as long-term engine damage.

Does your car need premium gas?

While everyday engines made for just driving around town run fine on regular gas, high-performance engines have an array of features that need premium gasoline to run their best. 

An engine designed for high performance may have a higher compression ratio or be turbocharged and needs premium gasoline to ensure proper combustion. 

That can also be the case with trucks, which are large, heavy-duty vehicles that need to maximize fuel efficiency. 

In today's advanced engines, if regular gasoline is used when premium gasoline is required, horsepower and fuel economy may decline as the electronic control unit – or ECU – makes adjustments to compensate.

You could also cause damage to your engine by causing pre-ignition, which in turn can cause a host of other issues.

The place to find out whether your car needs premium gasoline is either inside the fuel door or in the owner's manual. If the vehicle requires premium gasoline, there will be a sticker inside the fuel door that reads "premium unleaded fuel only" along with a minimum octane rating.

If your car requires premium gasoline, the best choice is to spend the extra money and fill up the tank. Your engine will run at an optimum level in both power and efficiency, and you can be sure pre-ignition won't occur. 

If the manufacturer only recommends premium gasoline, it's up to you to try both premium gas and regular gas, then try and notice any difference in performance. If there isn't any, regular gas is a safe choice.

If your car doesn't require or recommend premium gasoline, there's simply no benefit to using it. You'll be spending money at the pump that could go toward an oil change or new tires. 

Today's regular gasoline contains EPA-mandated additives to keep your engine running clean and smooth mile after mile. 

If you experience pre-ignition, knocking, or pinging, no matter what grade of gasoline you use, it's time to schedule an appointment with your mechanic to see what the problem is. 

Additionally, if the vehicle requires premium gas but you opt for regular gas instead, it could void your warranty. It's imperative to know this if you're leasing a car and don't want to incur additional expenses at the end of the lease term. 


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Is premium gas better?

It may seem like premium gas is a better choice for your car because it’s more expensive and possibly a higher-end product. The higher octane rating and fancy names given by fuel manufacturers make premium gasoline seem like something that can benefit your car.

But the truth is regular gas is a safe bet if your engine doesn’t require premium gasoline. 

Today, all grades of gasoline contain EPA-mandated additives to keep engines running clean. Detergents work to prevent the buildup of deposits and even remove old ones. Various manufacturers have their in-house detergents. Chevron’s Techron, for example, is one of the best-known brands. 

Enter the Top Tier Gasoline standard. Created by Audi, BMW, General Motors, Honda, Toyota, and Volkswagen, the Top Tier Gasoline standard ensures consumers get gasoline with an excellent additive package. The Top Tier standard requires a higher level of detergents in gasoline than required by the EPA. When you buy Top Tier gasoline, you can be sure it has an excellent additive package, no matter if it’s regular or premium. 

So rest assured, if premium gasoline isn’t required, your engine will run strong and clean on regular gasoline. 

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Premium gas differs by state and manufacturer

The octane rating of premium gasoline varies by state and is either 91 or 93. Either one qualifies as premium fuel, so if it's required, you're okay to fill up wherever you may be. 

Different fuel manufacturers have various formulas in their premium gas and use unique names to differentiate them from regular gas. 

Shell's premium gasoline is V-Power NiTRO+, which has four levels of protection against gunk, corrosion, wear, and friction. V-Power NiTRO+ is patented and the most advanced fuel ever produced by Shell.

ExxonMobil's premium gasoline is Synergy Supreme+ and contains high levels of detergents for cleaner fuel injectors and better fuel economy. Synergy Supreme+ can actually clean engine deposits left behind by other types of lower-quality, less-refined fuel. 

Wherever you decide to fill up with premium gas, a Top Tier manufacturer is the best bet so you can be sure you're getting the highest quality and a premier additive package. 

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Benefits of Using the Correct Gasoline

In the long term, using the grade of gasoline recommended by the manufacturer will allow your engine to run stronger and cleaner and get the best fuel economy. If you're shopping for used cars, you'll want one that's received the correct grade of gasoline for years of trouble-free driving and good fuel economy, too. 

What if you want to buy a used vehicle that's been well taken care of, but you don't want the hassle that's typical of a traditional dealership? And at the same time, how can you be assured you're getting the best price? Enter Shift, which offers fair, no-haggle prices driven by powerful machine learning algorithms and tons of data. And thanks to Shift's certified mechanics who perform 150-point inspections on each vehicle in their inventory, you know your used car – no matter what type of gasoline it requires – will be as good as new.

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Author
Shift Editorial Team