The Forester typically uses a silicate-free, ethylene glycol–based coolant in a Hybrid Organic Acid Technology (HOAT) formulation, with Subaru’s Genuine Long Life Coolant as the preferred option. It is usually sold premixed in a 50/50 ratio with distilled water, though concentrate versions are available for DIY mixing.
Cooling systems in Subarus are designed to resist corrosion and overheating across varied climates and driving conditions. Using the correct coolant helps protect the engine, heater core, and radiator, while improper coolant can lead to reduced efficiency and potential damage. Always follow the model year guidance in your owner’s manual and avoid mixing incompatible coolants.
Coolant options for a Forester
Below are the main options to consider when purchasing coolant for a Forester. Choose products that are HOAT or OAT, silicate-free, and explicitly labeled as compatible with Subaru engines.
- Subaru Genuine Long Life Coolant (HOAT, ethylene glycol–based, silicate-free) — available in premixed 50/50 and concentrate forms.
- Other reputable HOAT coolants that are clearly marked as compatible with Subaru engines and are silicate-free and phosphate-free, suitable for ethylene glycol–based systems.
- Distilled water for mixing if you buy coolant concentrate (never use tap water).
When shopping, check that the product explicitly states compatibility with Subaru engines and that it is designed to be silicate-free and pH-balanced. Do not mix different coolant families without flushing the system first, as incompatible mixtures can cause cooling system damage.
Maintenance and best practices
Maintaining the Forester’s cooling system involves regular checks and following the manufacturer’s recommended service intervals. The coolant should be inspected for level, color, and signs of contamination, and replaced according to the owner’s manual or service schedule.
- Check the coolant level when the engine is cold and inspect for color or sediment changes.
- Look for obvious leaks around hoses, the radiator, and the water pump; address any leaks promptly.
- Replace coolant at the intervals specified in your manual, typically with long-life HOAT coolant; do not extend beyond the recommended period.
- If overheating or heater performance declines, have the cooling system pressure-tested and flushed if needed.
Following these practices helps prevent corrosion, freezing, and overheating, preserving engine longevity and climate comfort inside the vehicle.
Notes on mixing and compatibility
Always use distilled water to dilute concentrates, and never mix coolant types unless the system has been thoroughly flushed. If in doubt, consult a Subaru dealer or a trusted mechanic to confirm that your chosen coolant meets the vehicle’s specifications for your exact model year.
Summary
The Subaru Forester’s cooling system is designed for a silicate-free, ethylene glycol–based HOAT coolant. The recommended path is Subaru Genuine Long Life Coolant, either premixed or concentrated for dilution with distilled water. Use compatible, silicate-free HOAT/OAT coolants and adhere to your owner’s manual for replacement intervals and service guidance. Proper coolant selection and maintenance protect the engine and cooling components across climates and driving conditions.
Can I use universal coolant in my Subaru?
Every vehicle manufacturer, including Subaru has developed its own coolant or requires a particular coolant that is unique to explicit years and models.
Do Subaru's need special coolant?
Every vehicle manufacturer, including Subaru has developed its own coolant or requires a specific coolant that is unique to individual years and models. There are many colors of coolants to help distinguish each including blue, purple yellow, green, red, and orange.
What coolant can I put in my Subaru Forester?
- PEAK Original Equipment Technology Asian Blue Pre-Mixed Engine Coolant / Antifreeze.
- ShopPro Yellow Pre-Mixed 50/50 Engine Coolant / Antifreeze.
- PEAK Original Equipment Technology Asian Blue Concentrate Engine Coolant / Antifreeze.
- Prestone Yellow Pre-Mixed Engine Coolant / Antifreeze.
What color coolant does a Subaru use?
This will hold true in most all Subaru Outbacks, Impreza, Forester, Legacy and WRX models. If you own a 1999 to 2008 SOHC 2.5l you should use the O.E. Subaru Long Life Coolant that is green in color pictured below.