WRX Gas Type: Does The Subaru WRX Need Premium Gas?

Subaru has a long history of designing and developing high-performance vehicles. This has made it one of the most popular vehicle brands in the United States and worldwide. 

So, do Subaru WRXs need premium gas? 

Does The Subaru WRX Need Premium Gas?

The Subaru WRX is a high-performance vehicle that requires premium unleaded gas of 91 octanes or higher for optimum performance. However, you should check your manual for the appropriate fuel for your specific model and trim level of your Subaru WRX STI. 

High-performance Subaru vehicle models like the WRX, WRX STI, and BRZ come standard with the premium gas requirement. 

These vehicles come with a potent engine under the hood that will give you the best power output on high octane premium gas. 

This doesn’t mean that the mentioned vehicles cannot run on low octane regular gas.

You risk losing efficiency and a great deal of performance when you fill them up with regular gas. 

Some trim levels of the WRX come with the strict recommendation of the minimum octane level to use. 

Do you have to run premium in WRX?

It is not a must that you run your Subaru WRX on premium gas. However, since it is a high-performance vehicle, the premium gas is the most ideal for this model.

If you fail to find premium gas in your next gas station, you can go ahead and fill it up with regular gas. 

There are normally three or more classes of gasoline available at most gas stations in America. 

Octane numbers must be prominently posted on each of these gasoline classes in accordance with regulations. 

Your Subaru WRX will work best with premium and super-premium gas. 

Fuel octane and grades that are readily available in many gas stations include the regular of octane 87, midgrade (plus) of octane level between 89-90, premium gas of octane level 91 – 92, and super-premium with octane number 93 to 94. 

The higher the octane level, the more expensive the gas will cost. 

Octane Rating and Performance of your Subaru WRX

Fuel combines with air and is heated by compression in the combustion chamber of a gas-powered internal combustion engine.

Boxer engines have pistons that move sideways in response to a spark, which subsequently powers the crankshaft and drives the drive wheels. 

The fuel-air combination can ignite on its own without the need of a spark, simply by the compression force exerted. 

Preignition is a dangerous occurrence that happens when the engine makes a knocking or pinging noise while running. 

Refineries started measuring their fuel against an isooctane standard. This is a hydrocarbon that is commonly found in gasoline and helps to prevent this preignition. 

The octane rating of gasoline has no bearing on its energy content. 

The octane rating of gas simply indicates how probable it is that the fuel will start a blaze before it burns completely in the combustion chamber. 

Recent Subaru models have been designed to take advantage of the enhanced design efficiency and advanced engine management systems. 

To get the most out of a tank of gas, the computer in the engine system may automatically modify the ignition timing to match the fuel’s octane rating. 

Subaru WRX: Regular Vs Premium Gas

Many turbocharged and supercharged vehicles come with the recommendation to use premium gas.

Your Subaru WRX will give you optimum performance when running on premium gas of octane 91 and above.

There are several grades of gasoline in the market today. 

You should not deviate from the recommended octane rating for your Subaru WRX. Most Subaru models will work fine with 87-octane gas. 

Powerful engines, like the WRX and BRZ will work best with at least 93-octane premium gas. 

Fuel quality and cleanliness are critical for your Subaru WRX. 

Make sure you don’t let your WRX use the wrong type of fuel as this will significantly affect the performance of your vehicle. Consider buying the recommended fuel. 

High-performance engines like that of the Subaru WRX and WRX STI will work well with high octane gas. 

Your owner’s manual will specify the minimum amount of octane required for your trim level.

The turbocharged and supercharged engine will similarly function better when running on high octane premium gas. 

Frequently Asked Questions (FAQs)

What happens if I put regular gas instead of premium once?

Subaru WRX, STI, and BRZ are high-performance vehicles that have been designed to function effectively even if you intentionally or accidentally put the wrong gas. 

Oftentimes the ideal quality of fuel may not be readily available, the system will simply adjust to the lower number of octane. 

Therefore, your vehicle will still function well. But you will not get the efficiency and performance that is typical of this high-performance vehicle. It is recommended that you use premium gas. 

Using regular gas occasionally is not a problem. 

Continuous use of low-level octane numbers will damage your engine in the long run. Always revert to the minimum amount of octane as recommended on the owner’s manual by the manufacturer.

This will ensure the optimal efficiency and longevity of your Subaru WRX engine. 

What fuel type is recommended on the Owner’s manual for Subaru WRX and BRZ?

The Subaru WRX and BRZ are popular performance models in the Subaru lineup. 

The engine of these vehicles should function well with unleaded gas with an octane level of 91 and above. 

Both models can run on gas with octane level 87 or higher with no bad effect on the performance or reliability of the engine. 

Use of lower octane gas may result in slight performance loss, but the Subaru WRX will automatically modify engine timing to prevent preignition. 

What is the best gas type for Subaru WRX STI?

Subaru WRX STI is a super performance vehicle that will work best with super-premium gas of octane level 93. 

This vehicle will also work well with premium gas of 91 octanes as recommended in the Owner’s Manual. 

You will get maximum performance from the WRX STI when you use higher octane gas. 

If you want to enjoy the high performance that is the base for the design of the Subaru WRX, then pay the extra few bucks for the premium gas of 91 octane or higher.

This will guarantee that you get value for your money and reduce the chances of your engine knocking. 

What happens if I fill my regular gas Subaru model with Premium gas?

When you fill your tank with high-octane premium gas when the regular is recommended, you will not get the additional benefits of premium gas. 

Don’t go beyond the specified octane level for your vehicle. 

Check your owner’s manual for the recommended octane level for your model. 

Filling up your vehicle with higher than recommended octane will not harm your engine, but it will hurt your wallet unnecessarily. 

Premium gas is more costly than regular gas. 

Therefore, filling your regular gas engine with premium gas is a waste of money. 

You will enjoy the additional benefits of cleaning your engine. But this can also be achieved using detergents and additives that will achieve the same purpose. 

Prolonged use of the wrong fuel may damage your engine and reduce the efficiency of your engine. 

Is it ok to use ethanol gas on Subaru WRX?

Ethanol is a plant-based fuel that has a lower chemical density than gasoline. 

However, ethanol fuels have a far higher octane rating. 

Most of the gasoline sold in America today contains roughly 10 percent ethanol and 90 percent pure gasoline to minimize our dependency on oil supply. 

E85 flex fuel and newer ethanol blends, including E15 and E30 are now available in many gas stations. 

You can safely use this gas on your Subaru WRX. The proportion of ethanol is indicated by the number after E.

Ethanol makes roughly 30 percent of E30 FlexFuel. 

But, before you use this type of gas on your Subaru WRX, check your owner’s manual for the recommended ethanol mixes that are safe for your specific trim.