Coolant is Critical to your Subaru:
When adding or replacing coolant, or servicing the cooling system, always use Genuine Subaru Long Life Coolant (P/N SOA868V9210). It’s a phosphate (non-amine) type and is specially formulated for all Subaru vehicles, which are equipped with aluminum engines and radiators. Coolant of other types may not provide the proper protection against corrosion of aluminum parts.
Subaru approved this coolant for optimum performance because it outperforms other types. Subaru Long Life Coolant never allows silicate gel to form, causing radiator plugging and, therefore, overheating. It’s available in one-gallon bottles, meets all OEM specifications and is required for warranty service.
As always, refer to the Owners Handbook and the Subaru service manual for each specific year and model.