The Forester’s cooling system uses a premixed ethylene glycol–based coolant designed for aluminum engines. The simplest, most reliable choice is Subaru Genuine Long-Life Coolant (premixed 50/50). If you use a non‑OEM coolant, make sure it meets Subaru’s specifications and is compatible with aluminum engines; avoid Dex-Cool or other incompatible formulations.
Understanding the coolant requirements for the 2020 Forester
Subaru engineers the Forester with an aluminum engine and requires a corrosion-inhibiting coolant that matches Subaru’s specific chemistry. The recommended route is Subaru’s own long-life coolant, but you may use a third‑party product only if it clearly meets Subaru’s requirements (ethylene glycol–based, HOAT or equivalent, silicate‑free, and compatible with aluminum). Always verify packaging and the vehicle manual before purchase.
Recommended coolant options
Before listing options, consider these selection criteria to ensure compatibility and performance:
- Choose a premixed ethylene glycol–based coolant labeled for aluminum engines.
- Prefer Subaru Genuine Long-Life Coolant or a reputable third‑party coolant that explicitly meets Subaru specifications.
- Avoid Dex-Cool (orange) and green universal coolants unless they are stated to be compatible with Subaru engines.
- Do not mix different coolant types; if switching formulas, perform a complete system flush.
In practical terms, the safest approach is to use Subaru Genuine Long-Life Coolant or a third‑party coolant that carries a Subaru compatibility statement. Always check the label and your manual for exact specifications and regional recommendations.
Maintenance and service considerations
Replacement intervals can vary by market and driving conditions, but Subaru generally recommends inspecting and replacing coolant at intervals up to 10 years or about 100,000 miles, whichever comes first. When performing a coolant change, use the specified coolant type and follow proper flushing procedures to remove old coolant and contaminants.
Summary
For a 2020 Subaru Forester, use a premixed ethylene glycol–based coolant that meets Subaru’s specifications, with Subaru Genuine Long-Life Coolant as the primary option. If using a third‑party coolant, ensure it is explicitly compatible with Subaru engines and does not contain incompatible additives. Follow the owner’s manual for replacement intervals and flushing procedures.