Understanding Grades of Gas

Since gas prices seem to be constantly fluctuating, usually in the upward and rarely in the downward, everyone can surely use help in saving some money at the pump. One of the best ways to save money on anything, gasoline included, is to understand what it is that you are buying. To be able to understand gasoline is not as difficult as many people would think, since all that this really entails is learning about the various grades of gas that are sold at a gas station.

No matter which gas station you go to, there are on average only three grades (Regular, Midgrade or Plus, and Premium) of gasoline that are sold. These grades have been based off of the octane ratings that the petroleum industry and government developed. As you can no doubt easily imagine, the higher the octane the more difficult it is to produce. What this means is that, as anyone who has ever studied economics knows, the more difficult an item is to produce, the higher it costs to make. This is illustrated quite nicely at the local pump through the higher cost of premium gasoline. But what is the real difference in the various octane ratings?

Briefly, what the octane rating is used for is symbolizing the rate which the gasoline burns at, in other words the volatility of the gasoline. The higher the octane rating then there is less chance there is of pre-ignition and smoother better burning. Where as the lower the octane rating, the easier it is for the gasoline to burn, and that means that there is a greater chance for pre-ignition, other wise known as engine knocking. On average regular gasoline is rated as having an 87 octane, but can range from being equal to 85 octane to just under 88 octane, hence the 87 octane rating. Regular gasoline, since it has a lower octane rating is easier to burn and therefore more likely to produce engine knocking in higher performance vehicles. Midgrade gasoline usually has a rating of about 89, but it can also range from as low as 88 and as high as just under 90. Premium gas is going to usually be rated as 92, but can in actuality be anything that is above a 90.

In the end, there is a real reason for the different grades of gasoline. That reason is performance, and often the type of gasoline that is used is going to play a role in how an engine performs. What that role is exactly is covered in more depth in another article.