Updated at: 10-08-2023 - By: Lucas

With the price of gas going up, you may wonder if it’s okay to switch from premium to regular or regular to premium. But if we want to be responsible car owners, we need to pay attention to the fuel octane requirements and recommendations for our cars.

Modern cars have engine control units that are very smart and can adjust to changes in octane. To keep the engine from knocking, you shouldn’t change octanes too often.

The answer may be a little more complicated than you think, but in the end, there is always a clear choice that is best for you and your engine!

The Current State of Vehicle Gas Tolerances

At gas stations today, regular, unleaded gasoline is the fuel of choice for most car owners. At the pump, this choice is almost always marked with an 87-octane rating. Most car owners go to gas stations every day and see 87-octane gas.

But every so often, you find a gas station that doesn’t have regular unleaded gas. If you don’t know how cars are doing right now, it can be scary to find yourself in this situation.

Most cars made in the last ten or twenty years have technology that can tell the difference between different types of fuel octane. That means your engine won’t have to work hard if you have to use premium gas (91, 92, or 93-octane).

Modern cars have electronic fuel management systems that change the way they work when they find a different type of fuel in the tank. Most of the time, the engine will change the timing of the spark plugs and the fuel injection. What happened? A ride that was mostly smooth.

What’s the Difference Between Regular and Premium Gasoline?

Can I Switch From Regular To Premium Gas (2)

I’ve made it clear that most of the time, putting the wrong fuel in your tank once in a while or by accident won’t hurt your engine in the long run. But what’s the difference between the two? What about diesel fuel, though?

When you park next to a gas station, you’ll see a number next to each type of fuel. This is the same all over the country. The price tag for regular gas is “87.” Premium gas is marked with a number from 91 to 93.

There are different octane ratings, which are shown by the numbers. The higher the octane number, the more pressure a gas can take before it starts to burn or explode.

In reality, there aren’t many differences between gasoline with 87 octane and premium gasoline with 91 octane.

But over time, if you put regular gas in a car that needs premium gas, it will run less well. In the same way, a car that runs on regular gas won’t start right if you always put premium gas in it.

Frequency is the key to getting the right answer. Your car won’t be able to tell the difference between regular and premium gas until you keep giving it the wrong kind.

What Happens if You Switch from Premium to Regular Gas?

In the end, switching from expensive fuels to cheap fuels for a long time isn’t the best idea. But the sophisticated ECU (Engine Control Unit) in most modern cars can handle switching back and forth between premium and regular gas.

But what happens when you change types of octane over a longer time? Not only will the car’s performance go down, but you may also hear a “engine knock.”

If you put regular fuel in a premium engine, it will knock, which is not what you want. In the past, when your engine knocked, it could damage the parts inside.

Today, it’s not as big of a deal. Engine knock happens when unburned gasoline burns on its own in a way that the engine can’t handle.

The engine knocking is the main reason you shouldn’t put gas in your car that isn’t recommended. It can damage an engine over time because the gasoline burns at a different time than the pistons move.

What to Look for When Determining the Right Gasoline

Can I Switch From Regular To Premium Gas (3)

If you fill up with the wrong type of fuel by accident, the best thing to do is to chill out. If your car was made within the last ten years or so, the engine can handle it.

But people who own cars should try their best to know which fuels to put in them. What should you watch out for the next time you go to the pump to fill up?

Requiring Premium

There is a hard-and-fast rule that can help you, though. If your car needs premium gasoline (with the emphasis on “needs”), you should buy 91-octane fuel or higher as often as you can.

If your car needs premium fuel, that means it needs fuel with a higher octane level to perform at its best.

Many European cars, such as BMW, Audi, and Volkswagen, need their owners to buy premium gas. This is because they require more detergent additives to be put in their cars than the EPA does.

You can learn more about why these producers have such high standards by looking at the Top Tier Gasoline standards.

Not Requiring Premium

If your car doesn’t need premium gas, you don’t have to buy 91-plus grade gas. The key word here is “need.”

In the past, people would sometimes put premium gas in their car’s gas tank to clean it out. Why?

At one time, premium gasoline was better than regular octane gas because it had cleaners and additives that made it run better.

According to the Federal Trade Commission, all octane levels of gasoline in the United States today have all the necessary additives to power any car.

Why pay more for premium gas if regular gas works just fine for your car? There is no longer a need to upgrade your fuel to make it run better.

Recommending Premium

The last type of car is one that recommends premium gas but doesn’t have to use it. If you’re reading this article, it’s likely that you’re somewhere in this grey area.

There is no one answer that works for all of these cars and trucks. Unfortunately, many common cars, like the Ford F-150 and Mazda Miata, fall into this category.

The short answer is that buying regular gasoline won’t hurt your car. The car’s maker may say that premium gas makes the car run better, but regular gas won’t hurt your car.

Diesel Cars

When it comes to diesel cars, we have to be very serious about what we say. Do not put regular or premium gas in a diesel car, or anything else besides diesel.

Doing so will damage the insides in a way that can’t be fixed.


After a while, unleaded fuel will wear away the oil in your engine and cause a lot of damage.

Can you put diesel in a regular- or premium-gasoline car? Good question.

It never works out well!

Even though putting regular gas in a diesel car is probably the worst thing you can do, the second-worst thing you can do is the opposite. If you do that, you’ll need to flush your fuel lines.

The Bottom Line

If you aren’t sure if your car or truck’s fuel recommendation is right, there is a way to find out. Edmunds made two lists to help people figure out what fuel their cars really need.

Check out the list of Premium Recommended cars and Premium Required cars if your car was made between 2012 and 2019.

I hope that going over the basics of fuel octanes has helped you figure out what to do at the gas station. At the end of the day, there’s no need to be overly worried if you accidentally switch from premium to regular gas.

However, a responsible auto owner should pay attention to their car’s needs and fill their engines accordingly.