Can I use regular coolant in a Subaru?
The short answer is no—you should not use regular green or universal coolant in a Subaru. Use Subaru Genuine Long Life Coolant or another coolant that is silicate-free and explicitly compatible with Subaru engines and aluminum components.
Subaru’s cooling system is designed around a long-life, silicate-free formulation that protects aluminum parts, seals, and radiator passages. Using the wrong type can lead to corrosion, deposits, reduced cooling efficiency, and potential warranty issues. This article explains how to identify the right coolant, why regular coolant is risky, and what to do if the wrong coolant was already used.
What Subaru requires
Subaru recommends a long-life, silicate-free coolant designed for mixed-metal and aluminum engines. The right coolant is typically labeled for use with all makes/models or specifically for Subaru, and may come premixed (50/50) or as a concentrate to mix with distilled water as directed in the manual.
How to identify the correct coolant
Check your owner’s manual for the exact specification. Look for language such as silicate-free, OAT/HOAT chemistry, and compatibility with aluminum engines. If in doubt, choose Subaru Genuine Long Life Coolant or an equivalent product that explicitly meets OEM requirements.
Before you choose a coolant, consider these options:
- Subaru Genuine Long Life Coolant (blue, silicate-free, often sold premixed or as concentrate per the manual).
- High-quality, silicate-free universal coolant labeled as safe for all makes/models and approved for aluminum engines.
- Other brand coolants that meet the OEM specification for Subaru (HOAT/OAT, silicate-free) and clearly state compatibility with aluminum engines.
Using the correct coolant helps protect the radiator, heater core, water pump seals, and the overall longevity of the cooling system.
Why regular coolant is risky
Regular or green coolant often contains silicates or additives that are not ideal for Subaru’s aluminum engines. Using the wrong coolant can accelerate corrosion, cause deposits or gel formation, and reduce cooling efficiency. Mixing different coolant chemistries can create unpredictable reactions, potentially clogging passages and harming the cooling system. In addition, using the wrong coolant can affect warranty coverage and future maintenance requirements.
- Silicate-containing coolants can corrode aluminum components over time.
- Some universal formulas are not fully compatible with Subaru engines or seals.
- Mixing different coolant types can lead to sludge, gel formation, or reduced heat transfer.
- Wrong coolant use can impact warranty and maintenance schedules.
To avoid these risks, always select a coolant that is explicitly compatible with Subaru or is clearly labeled as a universal, silicate-free option for all makes/models.
What to do if you already used the wrong coolant
If you’ve already added a non-SUBARU coolant or a regular green coolant not specified for Subaru, consider flushing the cooling system and refilling with the correct coolant. Do not continue driving long distances with an incompatible coolant, as it can worsen cooling performance or cause damage. A proper flush and refill typically involve draining the old coolant, flushing with distilled water or a dedicated flush product, then refilling with the correct silicate-free coolant.
- Stop driving if you notice overheating or leaks and have the vehicle inspected.
- Drain the cooling system completely and recycle the old coolant properly.
- Flushed the system with distilled water or a professional coolant flush until clear.
- Refill with Subaru Genuine Long Life Coolant or an equivalent silicate-free coolant, following the manual’s mixing instructions.
- Bleed the cooling system if required by your model, run the engine to operating temperature, and check for leaks and correct coolant level.
If you’re unsure about performing a flush, have a qualified technician handle the service to ensure the system is bled correctly and all air pockets are removed.
Maintenance tips
Keep your coolant level within the recommended range, monitor for signs of contamination or oil-in-coolant, and follow the maintenance schedule in your owner’s manual. Subarus with long-life coolant typically have a specified replacement interval; always refer to your model year’s guidance to maintain optimal cooling performance.
Summary
Subaru requires a silicate-free long-life coolant that is compatible with aluminum engine components. Do not use regular green or other non-approved coolants unless they are clearly labeled as Subaru-compatible or universal, silicate-free formulas that meet OEM specifications. If the wrong coolant has been used, have the system flushed and refilled with the correct coolant to protect the engine and cooling system integrity. When in doubt, consult a Subaru dealership or trusted automotive technician for guidance.
Does Subaru require 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.
Is it okay to use any coolant in my car?
No, you cannot use any coolant in your car; you must use the specific type recommended in your owner's manual. Mixing different coolant types can cause chemical reactions that lead to gelling, which can clog your cooling system and cause expensive damage and overheating. The color of the coolant is not a reliable way to determine compatibility.
This video explains the consequences of using the wrong coolant and how to identify the symptoms of an incompatible coolant: 57scar PROblemsYouTube · Feb 8, 2024
Why using the wrong coolant is dangerous
- Chemical reactions: Different coolant technologies (like OAT and IAT) have different chemical inhibitors. Mixing them can create a gel-like substance that blocks coolant passages, the water jackets, and the radiator.
- Damage to components: The gelling and chemical reactions can lead to corrosion and damage other vital parts, such as the water pump, head gaskets, and radiator.
- Overheating: A clogged cooling system can't effectively dissipate heat, leading to engine overheating, which can cause severe and costly engine repairs.
- Color is not a guide: The color of coolant is not a universal indicator of its type and can be misleading. Always check the owner's manual or the coolant bottle for the correct specification.
What to do if you're unsure
- Check the manual: The most reliable source of information is your vehicle's owner's manual. It will specify the correct type of coolant for your car.
- Look for universal coolants: If you don't know what coolant is currently in your system and can't perform a full flush, some "universal" coolants are formulated to be compatible with most other types, but a full flush is always the safest option.
- Perform a system flush: If you need to switch coolant types, the safest approach is to perform a full system flush to remove the old coolant entirely before adding the new, correct type. This is a job best left to a professional if you are not comfortable doing it yourself.
Can I put green coolant in my Subaru?
Absolutely not. Go to the dealership and get some super coolant, or at the very least, get the peak Japanese blue stuff.
Do I have to use Subaru coolant on Reddit?
Subaru super coolant has its own formulation. If you are just topping off your coolant I would suggest just buying the Subaru super coolant and using that (its best to use the 100% of the same coolant). If you are completely changing your coolant it doesn't really matter.
