The Difference between Premium and Regular Gas
If you manage a fleet of vehicles, you’re going to spend a significant amount of money on gasoline. In fact, it might be one of your highest [figures]. When your vehicles pull up to the pump, chances are good your drivers will see something like this:
But what do the numbers mean? They’re what’s called the Research Octane Number (RON) or the Anti-Knock Index (AKI). They refer to the ratio of iso-octane versus heptane in the gasoline. For example, gasoline with an octane rating of 90 means the gas is 90% iso-octane and 10% heptane. That’s all well and good, but how does it affect your fleet?
There are two ways for gasoline to ignite. The first is with a flame or spark, which is what a spark plug does. But if you compress gasoline enough it will ignite spontaneously, without the need for a spark or flame. When you compress gasoline along with air, you get a much larger ignition than if you just compressed gasoline by itself. Adding air to your gasoline is the job of a vehicle’s carburetor or fuel injectors. Compressing the gasoline along with air is the job of a vehicle’s pistons.
When the piston in an engine compresses gasoline before a spark plug fires, there’s always the possibility that the gasoline will ignite prematurely. If this happens before an engine is ready, the exploding gasoline will drive the pistons backwards. It’s like trying to walk through a revolving door while every few seconds some jerk pushes the glass in the wrong direction. When this happens in an engine, you get a knocking sound as the engine fights against itself. Not only is this bad for fuel efficiency, this can cause serious damage.
Gasoline with a higher octane number require more compression before it explodes, meaning that it’s less likely to explode in a piston before the spark plug sets it off. Because the gasoline has a high octane rating, gas companies charge more money for it.
What most people don’t know is that modern vehicle engines include a knock sensor which detects knocking and compensates by adjusting the amount of air included with the gasoline to prevent it from igniting prematurely.
There are two types of vehicles which can benefit from high octane gasoline. The first is the forty year old clunker, which has no knock sensor. The second is the ultra high-end fantasy car – we’re talking Lamborghini here – which has an engine designed to withstand gasoline compressed to extremes and convert the larger ignition into faster speeds.
So what’s the point of spending more money on premium gasoline for your fleet?
There isn’t any. Unless your fleet has record players for stereos or can hit 250 miles per hour on the highway, there’s no reason to buy premium gas.
Save money. Buy regular.
