Fuel Octane Number: Premium or Regular?

Surely at least a few times you have wondered when refueling if it is worth spending more on premium fuel. Most drivers choose to bypass the premium and use the cheaper regular unleaded gasoline. But have you ever wondered what exactly is the difference between the different octane numbers?

Most gas stations in the US offer three different octane levels:

• 87 – Regular

• 89 – Medium grade

• 91 to 93 – Premium

An octane rating, according to Exxon Mobile, measures a fuel’s ability to withstand engine knock or ping. The higher the octane, the more resistance the fuel has to ping during combustion. Certain gas stations may offer up to five different octane ratings. Other places may call their medium grade “plus” or “special” and their premium “super.” If the description confuses you, just look at the octane rating.

The benefits of regular unleaded gasoline

The single greatest benefit of using regular unleaded gasoline is the cost savings. Regular gasoline generally costs about 30 cents less per gallon than premium. Throughout the year, depending on how often you refuel, it can generate significant savings.

When it comes to the efficiency of regular gasoline, the Federal Trade Commission says there are no advantages to using premium gasoline in cars that don’t require it. The FTC states that using a higher octane rating in cars that do not require it will not lead to better gas mileage or a cleaner or faster running car.

You can find the recommended or required gasoline for your purchased or leased car in your owner’s manual. Currently, in most newer cars, engine control systems could compensate for low octane by monitoring knock activity and adjusting ignition advance to prevent knock. Basically, today’s sophisticated cars can effectively tune their engines on the fly.

When to consider mid-grade gas

The middle grade falls somewhere between regular and premium. There are very few cars that require or recommend mid-grade gasoline. People whose cars require premium sometimes use mid-grade gasoline to save money, but still use higher octane gasoline than normal.

Premium Gas – Is it worth the cost?

Different states have different regulations regarding what premium stands for, it usually starts at 91 and goes up to 93. The only cars that require premium gas are cars with high compression or turbocharged engines, to prevent engine knock. If your car does not require the use of premium or has a low compression engine, then there is no benefit to using premium.

Higher compression engines require higher octane so that the fuel does not ignite earlier in the combustion process and damage the engine. Octane brakes and controls fuel knock during fuel compression and knock.