What type of coolant for a 2018 Subaru Impreza?

The 2018 Impreza uses a blue, ethylene glycol-based long-life coolant designed for aluminum engines. The safest choice is Subaru Genuine Long Life Coolant (often sold as a 50/50 premixed solution) or an equivalent that clearly meets Subaru’s coolant specification for this model.

Overview of the coolant specification for the 2018 Impreza

Subaru recommends a long-life, ethylene glycol-based coolant that is compatible with aluminum engine components. You can use the OEM Subaru coolant or a high-quality aftermarket coolant that explicitly states compatibility with Subaru engines and meets the Subaru specification (silicate-free and phosphate-free). Premixed 50/50 formulations are common and convenient, but concentrates can be used if you dilute them with distilled water to the same final ratio.

Recommended coolant options

Below is a quick guide to the kinds of coolant you should consider. Each option preserves the cooling system’s corrosion protection and is suitable for the Impreza’s aluminum engine.

• Subaru Genuine Long Life Coolant (blue, ethylene glycol-based; available as 50/50 premixed or concentrate to dilute)


• Subaru Genuine Long Life Coolant Concentrate (to be mixed with distilled water to achieve the 50/50 rule)


• Any premium long-life coolant that explicitly lists compatibility with Subaru vehicles and meets Subaru’s specification (silicate-free, phosphate-free) for aluminum engines

When selecting an aftermarket alternative, always verify the product label for explicit Subaru compatibility and avoid coolants with silicates or additives not approved for Subaru engines. Mixing different coolant types can cause corrosion or clogging of the cooling system.

How to replace or top up the coolant correctly

Before listing the steps, note that proper filling and bleeding are important to prevent air pockets and overheating. If you’re unsure, consult a qualified mechanic. The guidance below covers common practice for a typical 2018 Impreza cooling system refresh.

• Drain the old coolant completely from the radiator and engine block, then flush with distilled water if a thorough cleaning is desired.


• Mix a 50/50 propor­tion of coolant to distilled water if using concentrate; use premixed coolant if that’s what you’ve purchased.


• Fill the system through the reservoir or radiator neck as advised in the owner’s manual, then start the engine with the heater on high and the cap off to bleed air. Watch for bubbling and continue adding coolant until the level remains steady.


• Once the system is full and air is bled, replace the cap and run the engine to operating temperature with the radiator fan cycling until it stabilizes. Check for leaks and recheck the level when cold.

Concluding: Using the correct coolant type and ensuring a proper fill with full air bleed are essential steps for maintaining optimal engine temperatures and avoiding corrosion inside the cooling system.

Maintenance interval and diagnostics

Routine coolant checks are part of the vehicle’s preventive maintenance. The Impreza typically follows Subaru’s long-life coolant schedule, which commonly targets a replacement interval around 100,000 miles (160,000 km) or 10 years, whichever comes first, though climate and driving conditions can affect this timeline. Always refer to the owner’s manual or your Subaru dealer for the exact interval and any climate-specific guidance.

Additionally, monitor for signs of trouble: a milky appearance in the reservoir (possible head gasket issue), low coolant level, sweet smell of coolant, overheating warnings, or coolant leaks. If any of these appear, have the cooling system inspected promptly.

Summary

For a 2018 Subaru Impreza, choose a blue, ethylene glycol-based long-life coolant designed for aluminum engines. Use Subaru Genuine Long Life Coolant (50/50 premixed or concentrate to be mixed with distilled water), or an aftermarket coolant clearly labeled as compatible with Subaru and meeting the OEM specification. Maintain the system with proper filling, bleeding, and periodic checks, and follow the manual’s service intervals to keep the cooling system in good condition.

What coolant does a 2018 Subaru Impreza take?

The recommended coolant for a 2018 Subaru Impreza is the Subaru Super Coolant (blue), which is a prediluted, long-life formula. Third-party options that are specifically for Asian vehicles and have a blue color are also compatible, such as Pentofrost A3 or Peak Original Equipment Technology Asian Vehicles Blue. Always choose a coolant labeled for Asian vehicles, and avoid mixing different types of coolant. 
Recommended coolant types

• Subaru Super Coolant: Subaru's factory-recommended blue, prediluted coolant. It is a long-life formula with a service interval of up to 100,000 miles. 
• Asian vehicle-specific blue coolants: Use products specifically designed for Asian vehicles, like Pentofrost A3 or Peak Original Equipment Technology Asian Vehicles Blue. These are formulated without silicates, borates, or amines that can harm Subaru's cooling system. 
• Color and type are key: It is crucial to use a coolant that is either the Subaru blue color or specifically labeled for Asian vehicles to ensure compatibility. 

Important considerations

• Avoid mixing: Do not mix different types of coolant, as this can cause damage to the cooling system. 
• Check your owner's manual: Always consult your owner's manual for the most accurate information and specifications for your vehicle. 
• Use pre-mixed coolant: The Subaru Super Coolant is prediluted, which ensures the correct water-to-coolant ratio for optimal performance and protection. If using a concentrate, you will need to mix it with distilled water according to the manufacturer's instructions. 

Do Subarus need special coolant?

Yes, Subarus need a specific coolant, primarily the factory-filled "Super Coolant," which is a special blue Subaru coolant. Before 2008, Subarus used a long-life green coolant. While a high-quality universal Asian blue coolant can be used, it's crucial to use the correct type for your specific Subaru model and year to ensure proper corrosion protection, especially for its aluminum engine components.
 
Coolant types and considerations

• Blue Subaru Super Coolant: This is the current standard, introduced after 2008, and is a premixed, long-life formula designed specifically for Subaru's aluminum engines. It has a much longer service interval than older coolants. 
• Green Subaru Long Life Coolant: This was used in Subarus before 2008. It is an ethylene glycol-based coolant that is not premixed and requires mixing with water to the correct ratio, which can be more challenging to get right. 
• Universal Asian Blue Coolant: A high-quality universal Asian blue coolant can be used as a substitute for Subaru's blue Super Coolant. This coolant is also designed to protect aluminum engines and can be a good option if you can't get the Subaru-brand product. 

Important tips

• Always check your owner's manual: The most accurate information for your specific Subaru model will be in your owner's manual. 
• Don't mix coolants: Never mix green and blue coolant, as they are not formulated to be compatible with each other. 
• Consider the warranty: If your car is still under warranty, using the specified Subaru coolant is recommended to avoid voiding the warranty. 
• Don't use universal coolants indiscriminately: While some universal coolants may work, it's crucial to ensure the universal coolant is specifically formulated for Asian vehicles to protect against corrosion and other damage. 

What color coolant does Subaru use?

IIRC Subaru recommends using blue for 2005+ but it was green until the official change in either 2008 or 2011, everything 2004 and earlier can use green or blue, but not a mix of both. Color means nothing. Now, flush all of that out, because you can't identify it only by color, and put in your choice of coolant.

What coolant does a Subaru Impreza use?

For most modern Subaru Imprezas, the correct coolant is Subaru's blue "Super Coolant", which is a 50/50 pre-mixed ethylene glycol-based formula designed for Asian vehicles and is often referred to as long-life or super long-life coolant. If using an aftermarket product, choose a yellow or blue Asian vehicle specific coolant from a reputable brand like Zerex or Prestone, as they are compatible with the original Subaru blue coolant. Avoid mixing different coolant types if possible, but if you must, an Asian blue coolant is generally compatible with Subaru's blue coolant.
 
Key coolant types for Subaru Impreza

• Blue Subaru Super Coolant: This is the factory-fill coolant for most Impreza models (typically 2009 and newer). It's a 50/50 pre-mixed formula that provides long-lasting protection and is designed specifically for Subaru cooling systems. 
• Aftermarket Asian Vehicle Coolant: If you can't get the Subaru-branded blue coolant, a high-quality aftermarket coolant labeled for Asian vehicles (often yellow or blue) is the next best option. 
• Older Models: Pre-2008 or certain models may have used green coolant, but blue coolant is the standard for more recent Impreza models. 

Important considerations

• Pre-mixed vs. Concentrate: Subaru's blue coolant is pre-mixed to ensure the correct water-to-coolant ratio. When using a concentrate, you must dilute it with distilled water to the correct ratio to avoid damaging the cooling system. 
• Color is not a perfect guide: While Subaru coolant is blue, many aftermarket coolants are available in different colors (e.g., yellow, orange) but are still compatible, so focus on the "Asian vehicle" specification rather than just the color. 
• Compatibility: While Subaru has stated that green and blue coolants are mixable, it is best to avoid mixing them to maintain optimal performance and longevity. Stick with either blue or a compatible Asian-specific coolant, as mixing them can impact the coolant's performance over time.