Difference Between Gasoline Grades

Gas Pump In CarDifference Between Gasoline Grades

 When you pull up to the gas station in the United States, you typically see three different choices. In many regions of the United States, excluding parts of the mountainous western United States, regular gas has an octane rating of 87, midgrade gas has an octane rating of 89, and premium gas has an octane rating or 91 or 92. Some vehicles require different grades of gasoline. Higher-performance cars often require midgrade or premium gas because their engines are designed for higher compression. Your vehicle owner’s manual will tell you what type of gas to use.


Why Have Different Grades?

If any type of gasoline is compressed too much it will spontaneously combust. Different octane ratings of gasoline ignite at different levels of compression. This does not mean that different grades of gasoline will provide a vehicle with more or fewer amounts of power, because all grades of gasoline contain about the same amount of energy. The different grades of gasoline are necessary for certain cars because their engines are designed to burn higher octane fuel, not because they are designed to go faster.


Regular Gas in a High Compression Engine

When a vehicle that needs premium gas, or gas with an octane rating of 91 or 92, gets filled up with regular gas that has an octane rating of 87, a knock or ping noise occurs. A knock or ping is when part of the fuel air mixture in one or more of your vehicle’s cylinders ignites before the spark plug fires. This happens because the gas is not formulated to be compressed as much as the piston is compressing it within the cylinder. It is essentially an explosion inside of the engine. This explosion can damage your engine.


Premium Gas in a Regular Engine

If premium gas is put into a regular engine it does nothing special. Putting premium gas in your car will not make you go faster, get better gas mileage, or have a cleaner engine. It will also not cause a knock, ping, or any other damaging effects to your engine. It will do exactly what regular gas does. The only difference is that it costs more.

What grade of gasoline does your car use? How often do you fill up? Leave a comment in the box below.

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