Have you ever wondered why there are different grades of gasoline? All grades of gasoline have what’s called an octane rating. So what is it and, more importantly, what should you use in your vehicles?

First of all, the engine in your vehicle burns fuel by compression – in other words, your engine is an internal combustion engine or burns fuel internally. The engine allows a mixture of air and fuel into the combustion area and a piston then compresses this mixture. Your spark plug then ignites this mixture causing an internally explosion that produces the power to run your engine.

Therefore, the octane rating tells you how much the gasoline can be compressed before it ignites spontaneously. Should gasoline ever ignite by compression rather than by the spark plug, then it would cause the engine to knock, possibly damaging your engine (think of it as taking a hammer striking the top part of your piston) – obviously this is not something that’s desirable.

Take regular gasoline with an 87 octane rating for example. This grade of gasoline would require less compression than gasoline with a 93 octane rating. Simply said, the higher the octane, the more compression it takes before spontaneous combustion occurs. Another way to look at it is that, the higher the octane, the slower the fuel burns, whereas a lower octane rated gasoline burns faster.