Leaded, Unleaded, And Octane – What???

Have you ever stopped at the pump to fill up your car with gas and looked critically at the signs and thought to yourself – what do these numbers mean? What exactly is “unleaded”? Well, if you think you fit this description, thank goodness you have this blog! I am about to take you to school! But, like, gas school. Anyway, read on.

So, let’s tackle the number issue. The numbers denote the octane levels of the gasoline, which differ and which are meant for different types of engines. The higher the octane, the higher performance your engine needs to be to use that type of gas.

What is octane, you ask? Well, even if you didn’t ask I am about to lay down some knowledge for you. So, octane (full name: isooctane) is a hydrocarbon that’s left in the fuel from the oil gas is refined from. Typically, hydrocarbons have a tendency to spontaneously combust before they’re really supposed to. Isooctane doesn’t do that, which is why the higher the octane level the less likely your fuel is to combust before it’s supposed to. If the fuel does combust too soon, you can get a “knock” in your engine.

You now might be asking yourself if your engine needs this higher octane fuel. Check your owner’s manual! If you have a regular vehicle, it can probably go without the high octane stuff. If your engine is more high performance, it might need the high octane. Always check. And if you do have a normal vehicle, using that higher octane fuel won’t magically make your engine into a race car engine. It’ll just be a waste of your money.

Now on to the “leaded” vs “unleaded” conversation. The quick and dirty of it is that in the 1920s, scientists were trying to figure out how to provide fuel for the rapidly expanding car market at a low cost. Regular low cost fuel made the engines knock, but the higher octane stuff was more expensive. But some genius figured out that if tetraethyl lead was added to the fuel, the octane level would increase with barely any impact on the cost. Sure, it gave everyone lead poisoning, and it wasn’t outlawed fully until the 1990s, but eh. It’s fine. Right? Right?!??