What Is The Difference Between Regular And Premium Gas?

Most cars use regular gas when filling up. There are a few that require premium though… The question is, why? What makes premium gas special and is it worth the extra money? This article explores the difference between regular and premium gas so you can hopefully save some money.


Regular gas has a rating of 87 octane, while mid-grade fuel is 89-90 and premium is usually 91 or 93.

Octane ratings are a measurement of fuel stability. They’re based on the pressure at which a gas will spontaneously combust. The numbers are actually an average between motor octane rating (MOR) and research octane rating (RON). The higher the number, the more stable the fuel.


The fuel your engine burns is a controlled combustion. The spark plug ignites a flame and burns throughout the cylinder until all of the fuel inside is burned. In contrast spontaneous combustion happens when rising pressure and temperature from the primary combustion leads unburned fuel to ignite. If there’s competition between a controlled and a spontaneous combustion, the energy built up from the burning fuel will disperse unevenly. That is likely to damage the engine’s piston and places a lot of pressure on it before it enters the power stroke.

This used to be a bigger problem than it is now. Most modern engines use sensors to detect and delay the initial spark. This causes the controlled combustion to happen when compression isn’t at its highest. It’s important to note though, that even though cars are built to detect a possible spontaneous combustion, it can still cause the engine to run inefficiently.

This may all sound very confusing, that’s ok. The important thing to remember is: the higher the octane rating, the lower the chance that a detonation will happen at the wrong time.


If your card doesn’t require premium, then don’t waste your money. Gas is expensive as is, so don’t splurge if you don’t have to. Many drivers think that premium fuel will make your car perform better, but that’s not the case. The detergent additives in your fuel are actually more important than your octane level. The detergent will help clean your engine and enhance performance. Information about detergents probably won’t be in your cars owner’s manual but it will likely be available through the gas station you use


The wording in your owner’s manual is very important here. If it requires premium, then without a doubt, you should use premium. Engines with a high compression ratio will naturally need a higher octane to perform as required. Using premium when it’s required also saves you money on gas, because it burns more efficiently. The difference is especially noticeable in turbocharged engines.

If your car recommends premium the choice is up to you. You may notice improved performance using premium and perhaps improved fuel efficiency. The best way to know is by trying and testing both options and making notes as you go. If you do see better efficiency from premium, you’ll want to compare your efficiency to the savings you get from buying regular. When in doubt, always ask; our expert sales team and experienced service department would love to help.