Have you all ever wondered what exactly is meant by the numbers on the pumps at the gas station? Do you also wonder why gas has to be qualified as “unleaded” on the pump? Well, we have written a great blog about both of these subjects that will hopefully answer all of your most burning questions!

First, come the numbers on the pumps. These indicate the octane level of the gasoline. The higher the octane level, the higher performance of engine it’s supposed to go into. What is octane, you may be asking now? When gasoline is refined from oil, several molecules called hydrocarbons remain in the gasoline. One of these hydrocarbons is isooctane, or just plain old octane. The other hydrocarbons have a lower ignition temperature, which means that they’ll combust under the slightest amount of heat and pressure. Octane is more resistant to that, which means it can withstand more pressure from the pistons in your engine and therefore won’t create a “knock” when it combusts.

A word of caution: don’t use higher octane gasoline in your regular engine unless your owner’s manual actively says to use higher octane gasoline! All you’ll be doing is wasting your money! But, if your manual does say to use the high-test stuff, do it. Otherwise, you’ll hurt your engine. It’s a fickle world we live in, folks.

Finally, that “unleaded” buzzword. A long time ago in a galaxy far far away (aka America in the 1920s), some scientists figured out that if gasoline had a low octane rating and made engines knock, they could just add tetraethyl lead to the gasoline and it’d kill both of those birds with one lead stone. Sure, everyone in the factories kept dying and the average American had a seriously unhealthy level of lead in their bloodstream, but it kept gas cheap! This persisted until the 1960s and was outlawed completely in the 1990s. After that, the average lead level in the blood of Americans went down by 75%. That’s a lot.