We’ve written extensively about the Subaru Impreza and WRX, its capabilities, and various features on this blog. Today, we will talk about what fuel this sedan needs and what fuels are strictly prohibited. Let’s start with a quick answer:
Most generations of the Subaru Impreza’s with a non-turbocharged engine make use of regular unleaded gasoline with an octane of 87. Subaru Impreza’s with a turbocharged engine make use of premium gasoline with an octane of 91. Impreza WRX’s also have a turbocharged engine, but they make use of premium gasoline with an octane of 93.
However, that doesn’t tell the whole story. Below we’ve outlined recommendations and requirements for different kinds of fuels and fuel additives. We’ll also go into detail about the compatibility of the Impreza and WRX with oxygenated blends. Furthermore, we discuss the tank size of these generations. Read on!
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Fuel Requirements Per Generation
The type of gas you need for your vehicle depends on its engine, so it can change depending on the year and model of vehicle. For example, the type of gas for a Subaru Crosstrek always has an 87 rating, but with Subaru Impreza, it changes depending on the year and the engine. Turbo-charged engines from this manufacturer take a different type of gas.
- Subaru Imprezas manufactured between 2000 – 2003 with a 2.5L non-turbocharged engine take regular unleaded gasoline with an octane of 87. The 2.0L turbocharged engines take premium unleaded gasoline with an octane of 91 although 87 octane can be used temporarily
- Subaru Imprezas manufactured between 2003 – 2007 with a 2.5L non-turbocharged engine take regular unleaded gasoline with an octane of 87. The 2.0L turbocharged engines take premium unleaded gasoline with an octane of 91. The WRX with a 2.5L turobcharged engine takes premium unleaded gasoline with an octane of 93.
- Subaru Imprezas manufactured between 2007 – 2021 with a non-turbocharged engine take regular unleaded gasoline with an octane of 87. The turbocharged engines take premium unleaded gasoline with an octane of 91. The WRX with a turbocharged engine takes premium unleaded gasoline with an octane of 93.
Also read: Absolute Best Years Of The Subaru Impreza
Now that you have a clear image of what fuel you should use with which model year and engine type, it’s also important to talk about premium gasoline. The reason for this is that many people wonder whether or not premium gasoline isn’t a better choice overall, even for the engines for which regular gasoline is recommended.
It’s essential to know that premium gasoline (with an octane of 91 or higher) is only helpful for engines that are designed for this fuel. This is because higher octane fuel does not give the Impreza any performance or durability benefits if the engine is not designed for premium gasoline.
Instead, you’ll be paying for more expensive gasoline that does not do anything special for your car. Therefore, it’s recommended you stick to the guidelines mentioned above.
Furthermore, using regular gasoline where premium gasoline is recommended will damage the engine and the fuel system. More on that in the subheading ‘Knocking Of The Engine After Refilling’ that you’ll find below.
Also read: The Exact Bolt Pattern Of A Subaru Impreza
Another topic we’ll need to talk about is the use of reformulated gasoline. Reformulated gasoline is gasoline that’s designed to burn more cleanly compared to regular, non-reformulated gasoline. This kind of fuel first became mandatory in California but is currently compulsory in more than 19 states/regions in the United States. Especially areas where the air quality is considered poor have rules regarding the use of reformulated gasoline.
It’s good to know that reformulated gasoline is 100% compatible with all the Subaru Impreza and the WRX generations. Subaru recommends the use of this fuel whenever it’s available. Also, you’ll get the same fuel economy compared to regular non-reformulated gasoline, and you won’t have to carry out any extra maintenance.
Oxygenated Blends Such As E-85
Besides reformulated gasoline, some gasolines have ethanol, methanol, or MTBE mixed into them. It’s important to know that these fuels are compatible with the Impreza, although you’ll have to keep a close eye on the percentages used in your fuel. The guidelines are as follows:
- All generations of the Subaru Impreza can use fuel with methanol although the fuel should not exceed a maximum of 5% methanol. Also, the fuel should be accompanied by sufficient quantities of the proper cosolvents and corrosion inhibitors required toprevent damage to the fuel system.
- Subaru Imprezas manufactured before 2016 can use fuel with a maximum of 10% ethanol (E-10), E-15 and E-85 are therefore not allowed. Imprezas manfuctured after 2016 can use fuel with a maximum of 15% ethanol (E-10 and E-15) but E-85 is not allowed.
- All Subaru Imprezas can use fuel with MTBE although the fuel should not exceel a maximum of 15% MTBE.
Not keeping to these guidelines will result in engine knock (more about that in the subheading below), the check engine light coming on, and the vehicle reducing speed to prevent heavy damage.
Gasoline With Additives
Online, many additives are available for the fuel of your Impreza that, according to their advertising, help your car reach peak performance or increase the durability of the fuel system and engine. Subaru strongly advises against the use of these fuels for the Impreza.
The reason for this is that some additives will contain silicon or metallics that will damage the engine and fuel system when they are used. Damage that’s caused this way does not fall under the warranty of the vehicle.
Instead of using additives, Subaru advises you to stick to the guidelines we’ve given so far in this article regarding the quality of the fuel. Furthermore, it’s recommended you only buy fuel from certified TOP TIER gas retailers. These retailers can be found via toptiergas.com.
TOP TIER gas contains all the necessary additives for your Impreza. This will help the car reach optimum performance while simultaneously cleaning the engine of possible deposits.
Knocking Of The Engine After Refueling
In some cases, you’ll hear a knocking sound coming from the engine. If this is a slight knocking sound, please know that this is entirely normal. Especially in situations where the engine is performing at or near-maximum capacity, a slight engine knock may be heard.
However, a problem does occur when this knocking sound becomes louder and louder. Especially if you just refilled your car, you may have a significant problem. In this case, you’ve likely used fuel with a lower than recommended octane rating.
If you hear a loud knocking noise, it’s recommended that you stop the car immediately and contact your dealer. Your car likely needs to be drained of the fuel you’re currently using. Furthermore, the fuel filter will need to be replaced, and the car’s memory will need to be reset by disconnecting and reconnecting the battery.
Fuel Tank Size Per Generation
- Subaru Imprezas manufactured between 2000 – 2007 have a fuel tank size of 15.9 gallons (60 liters).
- Subaru Imprezas manufactured between 2007 – 2011 have a fuel tank size of 16.9 gallons (64 liters).
- Subaru Imprezas manufactured between 2012 – 2016 have a fuel tank size of 14.5 gallons (55 liters).
- Subaru Imprezas manufactured between 2016 – Present-day have a fuel tank size of 13.2 gallons (50 liters).
Hi! My name is Stefan; I’m the owner and lead writer at TheDriverAdviser.com.
I’m an active writer on this blog myself, as well as a novice car mechanic. For the really technical stuff, I find writers with experience as a mechanic or who have studied mechanical engineering.
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