Updated at: 27-06-2022 - By: Lucas

Have you ever put the wrong kind of gas in your car by accident and wondered what would happen if you mixed regular and premium gas?

Mixing premium and regular gas is not usually a good idea, but it won’t have much of an effect on how a car runs right away. Only high-end cars that need gas with higher octane may see a small drop in performance or engine knocking.

Keeping this in mind, this general answer does have a few caveats!

So, in this article, I’ll talk more about premium and regular gas and what could happen to your car if you mix them.

Mixing Premium Gas with Regular Gas

Can You Mix Regular And Premium Gas

I’ve been stuck without gas for my high-end car more than once or twice. But I can say for sure that my car was fine with regular gas on those few occasions.

If you mix premium gas (which has a higher octane) with regular gas (which has a lower octane), the fuel tank will have an octane rating that is a mix of the two types of gas (mid-grade).

From a mathematical point of view, if you mixed equal parts of regular gas (grade 87) and premium gas (grade 91), you’d get a combined grade of 89!

This will, of course, depend on how much of each you put in!

A lower octane will hurt the performance of high-end cars.

Still, the best thing to do if your car needs regular fuel is to fill up with regular fuel. Using premium fuel won’t help you in any way.

And if you have a nice car, fill it up with good gas (if you can).

If there aren’t any premium pumps and you’re afraid your car might knock, don’t worry. Just fill up with enough regular gas to get to the next station.

Today, many pump stations also sell octane boosters.

If you don’t want to take any chances with your car engine, these are very helpful. You can buy one and use it to raise the octane level of your fuel.

What Happens When You Mix Premium with Regular Gas in a Regular Gas Vehicle?

Most cars don’t benefit from using premium gas in a regular gas car.

Here’s what you should expect when you put premium gas in a regular car!

1. There May Be No Extra Benefits if the Car Doesn’t Need Premium Gas

According to the Federal Trade Commission, there are often no benefits to using gasoline with a higher octane rating than what is recommended.

Your engine won’t run any faster or better than it did before. You’ll only end up paying more.

Still, mixing premium gas and regular gas can sometimes make a blend that makes your car run a little faster or get a little better mileage.

2. Premium Gas and Regular Gas Have Varying Octane Ratings

Some states call gasoline “premium” when it has an octane rating of 92, while others do so when it has an octane rating of 90.

Most gas stations sell three grades of octane:

Regular grade: 87 octanes

Mid-grade: 89 octanes

Premium grade: 91-93 octanes

So, you might find that the “premium” gas you put in your car isn’t really a “high-octane” fuel.

3. Heavier Cars or Turbochargers Need Premium Gas

Have you got a regular car? Is it a car with a big engine or one that has turbochargers?

If you have a regular car, there’s no need to use premium gas. You’ll spend more for almost no extra benefit.

But you have to use high-octane gas if your car has turbochargers or a big engine. That’s because these kinds of cars have higher compression ratios, and if you don’t use premium fuel, the engine might knock.

Also, if you have an old car, I think you should use premium gas instead of regular.

What Happens if You Mix Regular with Premium Gas in a Premium Gas Car?

Can You Mix Regular And Premium Gas-3

Using regular gas with an octane rating of 87 in a premium fuel car caused the engine to knock a few years ago. This meant that the car would start knocking as soon as it got gas, even before it left the gas station.

But things are different today. If you mistakenly put regular gas in your premium car, the ECU (Engine Control Unit) will change the performance and timing of the engine.

So, the lower-octane gas will not hurt your car at all.

But even though you can work with lower-octane fuel, it’s not a good idea to do so just because it’s cheaper.

The car was made to run on higher-octane fuel, so it’s best to use it as much as possible.

How Does Premium Differ from Regular Gas?

To know how premium gas is different from regular gas, you need to know how high the octane rating is.

Regular gas has a lower octane rating than premium. Depending on where you live, it’s between 91 and 93.

In fact, there are places where the octane rating of premium gas is higher than 93. Regular gas, on the other hand, has an octane level of 87.

The octane rating of gasoline shows when it is likely that the fuel will burn at the wrong time. When the octane rating is higher, there is less chance that the fuel will burn at the wrong time.

When combustion or pre-ignition start too early or too late, it makes a pinging or knocking sound. This is why it is also called “engine knock.”

Higher octane gasoline is best for keeping an engine from knocking, which might explain why people used to use premium gas in regular gas cars in the past.

Your car is usually safe from occasional low-level pings. But knocking your engine over and over again speeds up wear and tear, which hurts your engine.

Final thoughts on mixing premium and regular gas

Most of the time, you shouldn’t mix premium and regular gas in any car. If your car is a premium, you should use premium gas. If it’s a regular, you should use regular gas.

If you mix the two, it won’t help a car that’s meant to run on regular gas, and if it’s meant to run on premium gas, it might not run as smoothly. Stick to the octane level of your car, unless it’s not possible.

Before you can use premium fuel in your regular car, consult automobile experts first. But don’t believe the common myth that regular cars that run on premium fuel handle and perform better.

The most important things for any vehicle are regular maintenance and checkups. With the two, your car will always run at its best.

Frequently Asked Questions (FAQs)

Here are some of the most common questions about mixing regular and premium gas.

Can You Mix Regular and Premium Gas at the Pump?

You can mix regular and premium gas to get a mid-grade octane. Most gas stations do this to get a mid-grade level of octane gas.

But putting regular gas in a premium car will make it less efficient and make it lose power. With each drop of lower octane, it’s likely that your car won’t run as well over time.

So, if your car runs on regular gas, pure low-octane gas will work well in it. Adding premium gas to regular gas is a waste of money because it doesn’t help the car in any way.

How Do I Know the Type of Gas to Use?

When you buy a car, you need to know what kind of gas it takes.

Look at the inside of the fuel door to find out how. There will be a label telling you what kind of gas to put in that car.

Do Turbocharged Cars Need Premium Fuel?

Most car manufacturers who make cars with turbochargers say that premium fuel is best for them.

But always check your owner’s manual to be sure. It tells you everything about your car, like what kind of gas you should use.