Man pumping gas at the pump.

Premium vs. Regular gas

Updated December 1, 2016 . AmFam Team

Knowing the difference between premium vs. regular gas can help get more out of your car, and maybe save money at the pump, too!

Cars do more than just get us from point A to point B. They empower us to accomplish daily tasks and chores, take fun excursions, travel to visit loved ones and pursue our dreams.

That’s why it’s smart to give cars the TLC they need! But when it comes to the basics, like fueling up, have you ever wondered what’s the difference between premium vs. regular gas?

We’ve got you covered. Here’s some helpful info to keep in mind before the gas gauge hits “E.”

Numbers, Octane and ‘Knocking’

Each time you pull up to the gas pump, you’re typically faced with three choices when it comes to unleaded gas: 87 (regular), 88–90 (midgrade), and 91–94 (premium). What do all those numbers mean? Put simply, they’re octane ratings that indicate the fuel’s ability to prevent “knocking” — that’s the sound you hear when the gas and air mixture isn’t burning the way it should in your engine.

And, you guessed it, knocking isn’t so great for your car, either. It can reduce your engine’s performance, and over time, it can cause damage. So, the higher the octane number, the less likely you’ll experience knocking. But you’ll have to pay more for higher octane gas, since it costs more to produce.

Which Kind of Gas Should I Use?

So, is it better to use higher octane mid-grade or premium gas instead of regular? Good question.

On the one hand, higher octane gas can reduce knocking, so that would seem like a good reason to use it.

However, regular gas is recommended for most cars. This is especially true for post-1995 models equipped with a knock-sensor — a cool technological innovation that minimizes knocking, allowing you to use lower octane (and less expensive) gas. Nice!

Keep in mind, though, that some manufacturers recommend or even require higher octane gas for certain car models — usually those snazzy high-performance luxury cars with powerful high-compression engines. If your owner’s manual recommends using higher octane gas, take heed!

Sometimes Premium Might be Better

There are certain circumstances when it’s smarter to use higher octane gas, especially when you’re putting extra load on your engine, causing it to work harder. Driving through hilly areas, hauling heavy loads and hot weather can tax your engine, so you’ll definitely want to use higher octane gas. Your car probably will perform better, and you’ll avoid that annoying knocking, too.

By choosing the right kind of gas, you’ll get peace of mind knowing you’re taking steps to keep your engine healthier and happier in the long run.

Want to dig a little deeper and maximize your driving experience? Learn how to get better gas mileage and get the confidence you need when it comes to proper car maintenance.

Tools & Resources

Explore our tools and smart tips.