Which gasoline is best for your car - Premium or Regular?

When you pull up to the gas station, do you really know what gasoline grade you’re going to fill up with? If varying gas pump prices aren’t confusing enough, are you using the right kind of gasoline that your vehicle's engine requires? Do you really know what you’re getting by using premium over regular gasoline? 

It’s very simple actually. All it takes is to find out the car manufacturer's recommended grade of gasoline to use as specified in the vehicle’s owner’s manual.

Almost all gas stations normally offer three grades of fuel: Regular 91-octane, Mid-grade 93-octane, and Premium 95-octane. Some gas companies even offer 100-octane gas for high-octane requirements. These octane ratings can be identified through bright yellow stickers placed on every gas pump.

In general, most vehicles are designed to use regular octane or premium gasoline, but performance-oriented cars need premium or high-octane fuel. Here are a handful of helpful facts to guide your choice between premium vs. regular gas at the station.

Basic types of gasoline

• Regular – 91 Octane
• Mid-grade – 93 or higher Octane
• Premium – 95 -100 Octane

What is Octane Rating?

A gasoline's octane rating doesn’t mean its power; the number merely reflects how well the gasoline resists premature detonation in an engine resulting in what’s called "knocking" or "pinging" and locally known as "tope."

"Knocking" - This is a distinct and audible sound that can be heard from the engine, which is actually the detonation that occurs before its intended time in the combustion cycle and one that's not initiated by the spark plug. In short, it is the uncontrolled ignition of fuel caused by high temperatures and pressures inside the combustion chamber. It can be caused by using gasoline with a low octane rating. 

To prevent knocking, chemicals are mixed in to control how quickly the fuel burns. This is known as the Octane Rating of fuel as it measures a gasoline’s ability to resist engine knock. The higher the octane number, the more fuel can be compressed before it detonates. In short, fuels with a higher-octane rating are needed in high-compression engines that require more fuel to generate high horsepower. 

FAQ regarding regular vs. premium gasoline

What octane gasoline should I use in my vehicle?

Simply follow the octane rating as recommended by the car manufacturer as specified on the owner’s manual and on the gas filler cap.

What happens if I use a lower octane gasoline than required for my vehicle?

Even though modern engines have knock sensors, prolonged use of gasoline with a lower octane rating than recommended may result in engine knocking. Persistent knocking can lead to engine damage.

Will using a higher-octane gasoline than required improve fuel economy or performance?

Generally, no, It does not offer any performance or fuel-saving benefit. It would be best to follow what the car manufacturer specifies. The only time you need to switch to higher-octane fuel is when the engine knocks. 

There are exceptions to the rule, however. Some car engines can have higher power when using higher octane fuel. An example is the 2.5-liter Dynamic Pressure Turbo Skyactiv-G engine found in the Mazda CX-9 and CX-5. When used with high-octane fuel, the engine churns out 250 horsepower, up 19 from its advertised 231 horses, and an additional 14 Nm of torque.

That is why it is best to refer to your car's owner's manual.

Will higher-octane gasoline clean the engine better?

No, because all commercially available locally sold gasoline contains engine cleaning detergent additives to protect against harmful deposits, which are standard and are not dependent on their octane level.

When should you get premium gas?

If your vehicle owner’s manual suggests using premium gas, there is a reason. Cars that require premium gasoline have high-compression engines, turbochargers, and other high-performance aspects. Not using premium won’t necessarily hurt your engine, but you could lose some of the performance of that premium engine you paid for if you use regular or midgrade gas.

Are fuel additives needed?

If you’re already buying gasoline with the proper octane rating, these are unnecessary because all gasoline companies infuse different chemicals to boost octane levels. Some products may contain strong solvents, emulsifiers, and water-absorbing agents that should not be used with E10 gasoline.

Are there benefits from using the correct gasoline grade?

If your car does not recommend premium, you aren’t doing your vehicle any favors by getting it. Some car manufacturers specify “premium” gas because certain kinds of engines operate optimally with higher-octane fuel. If your owner’s manual doesn’t call for premium gas, your vehicle doesn’t need it. More importantly, you’ll also be saving money along the way.

Can you mix premium and regular gas?

Mixing different octanes will not improve your car engine’s performance. It is best to stick with the manufacturer’s recommendation for optimum performance.