Can I put 89 gas in my Subaru?

Yes, you can in many Subarus, but it depends on the exact model and year. Most Subaru engines are designed for regular 87 octane, while turbocharged or high-compression variants typically require higher octane (often 91–93). Always check the owner's manual or the fuel door sticker for your specific vehicle.

General octane guidance for Subaru models

The following guidance covers typical Subaru configurations, but exact requirements can vary by year and trim. Use the octane rating specified by your vehicle’s documentation for optimal performance and protection.

• Most non-turbo Subaru engines have 87 octane as the minimum requirement (regular unleaded). Using 89 is permissible in many cases but usually offers no significant performance benefit.


• 89 octane is considered mid-grade and is generally acceptable for many 87-rated engines, but it may not provide any measurable efficiency or power gains.


• Turbocharged or high-compression Subaru engines (such as certain WRX/STI models and some turbo variants) typically require higher octane fuel (often 91–93 octane). Using 89 in these engines may reduce performance or trigger protective timing adjustments.


• Always confirm the exact requirement for your model/year on theOwner’s Manual, the fuel-filler door sticker, or Subaru’s official support resources.

In short, follow the octane specified for your particular Subaru. 89 octane is fine for many everyday drivers with non-turbo engines, but it may not be appropriate for turbo or high-performance variants.

How octane affects performance and engine safety

Octane rating measures a fuel’s resistance to knocking, which is premature ignition inside the engine. Higher-compression and turbocharged engines rely on higher octane to prevent knocking and to allow optimal timing. If your engine is designed for 87 octane, using 89 typically won’t unlock extra power, and using fuel with too low an octane can cause knocking and reduce performance. If your engine requires higher octane, using only the recommended grade helps protect the engine and maintain efficiency.

Model-specific notes from Subaru family

Because Subaru offers a range of naturally aspirated and turbocharged engines across several models, octane needs can vary. The following notes reflect common, real-world guidance:

• Naturally aspirated 2.5L and other non-turbo Subaru engines commonly list 87 octane as the minimum; 89 can be used but may not yield noticeable improvements.


• Turbocharged variants (including WRX/STI and some turbocharged crossovers) usually call for higher octane fuel (generally 91–93 octane). 89 octane is generally not recommended for these engines.


• Always check the fuel requirements for your exact model year, as Subaru periodically adjusts recommendations with new engines or tuning.

Bottom line: your best bet is to follow the model-specific guidance. If your Subaru is not turbocharged and lists 87 as the minimum, 89 is acceptable but not necessary for performance gains. If you own a turbocharged model, plan for higher-octane fuel as specified by the manufacturer.

What to do if you accidentally fuel with 89 octane

If you ever fuel with 89 octane in a model that requires 87, you can usually continue driving normally, but monitor for any knocking or power loss. If your vehicle requires higher octane and you fueled with 89, you might notice reduced performance under load. In such cases:

• Drive normally and avoid high-load driving (like steep hills or rapid acceleration) until you can refuel with the correct octane.


• Next refuel, use the octane recommended by your manual or door sticker.


• If you notice persistent knocking, pinging, or reduced performance after fueling with 89, consult your dealership or a qualified mechanic for advice.

These steps help ensure you don’t cause unintended engine stress and that you stay within the engine’s designed performance envelope.

Summary

Most Subaru models tolerate 89 octane if the manual specifies 87 as the minimum, but it won’t magically improve performance. Turbocharged or high-compression Subarus typically require higher octane (91–93), and using 89 in those engines is not recommended. Always verify your exact requirements in the owner's manual or on the fuel door sticker, and adjust your fueling habits accordingly for optimal performance and engine longevity.

Bottom line

To be safe and to maximize efficiency and reliability, follow the octane grade specified for your specific Subaru model and year. If you’re unsure, contact a Subaru dealer or consult the official documentation for precise guidance.

Is it okay to put 89 gas instead of 91?

Yes, you can put 89 octane in a car that requires 91, but you may experience a slight reduction in performance and fuel economy. Modern cars with knock sensors can often adjust to the lower-octane fuel and prevent engine damage, especially in steady-state driving conditions. However, for optimal performance and to avoid potential long-term issues, it is best to refuel with the recommended 91 octane, especially when accelerating hard or under heavy loads. 
Potential consequences of using 89 octane

• Reduced performance: The engine's computer may retard the ignition timing to prevent knocking, which can lead to less power and acceleration. 
• Lower fuel efficiency: The vehicle may get fewer miles per gallon, potentially negating any small savings from the cheaper gas. 
• Engine knock: You might hear a "pinging" or "knocking" sound, especially during acceleration. 
• Engine damage: In the long term, consistently using a lower octane than recommended can potentially cause damage, though modern cars are designed to handle this better than older vehicles. 

What you should do

• Monitor for knocking: Listen for any pinging or knocking sounds, especially when accelerating.
• Drive conservatively: Avoid heavy loads and aggressive driving until you can refill with the correct 91 octane.
• Refill with 91 octane: Top off the tank with 91 octane fuel as soon as possible to restore the recommended octane level for your engine.
• Check your owner's manual: Your car's manual will have the most accurate information on the recommended fuel octane. 

Can Subarus take premium gas?

However, performance models such as the WRX STI and BRZ require premium gas to maintain peak performance. In regions with higher elevations, such as Colorado, where you can often find 85-octane fuel, Subaru recommends sticking with 87-octane fuel despite the lower air density.

What happens if I put 89 octane in my car?

Using 89 octane gas in a car designed for 87 octane gas will not harm the engine, but it is unlikely to provide any benefit like better performance or fuel efficiency. Conversely, using 89 octane in a car that requires premium (91 octane or higher) may lead to reduced performance or engine knocking as the engine adjusts to the lower-octane fuel. 
If your car is designed for 87 octane gas

• No harm, no benefit: Using 89 octane will not damage your engine, but your car's computer is not designed to take advantage of the higher rating, so you will likely not see any difference in performance or fuel economy.
• Waste of money: You are essentially paying more for a feature your car does not need, according to this Quora post. 

If your car is designed for 91 octane gas (or higher)

• Potential performance loss: Putting 89 octane in a high-performance engine can cause the engine to lose power and efficiency.
• Engine knock: The lower octane fuel may cause the engine to "knock" or "ping," but most modern cars have sensors that will adjust the engine timing to prevent damage. This adjustment, however, is what leads to the reduction in performance. 

How to know what octane to use

• Check the owner's manual: The recommended octane level is specified in your car's owner's manual. 
• Look for the sticker: There may also be a sticker with this information on the inside of the fuel door. 
• When in doubt: If you are unsure, it is best to consult a qualified mechanic or the vehicle manufacturer for guidance. 

What happens if I use 89 in a car that needs premium?

Other things to consider: failing to use high-octane fuel in your premium vehicle could cause engine knock or pinging, which sounds like there's a large woodpecker under your hood; you could experience damage to your components; and using the wrong octant level could even void your warranty.