Coolant is Critical to your Subaru:
Cooling System Conditioner
Whenever the coolant is changed, you must add Genuine Subaru Cooling System Conditioner, (P/N SOA635071). It’s been tested and approved for Subaru aluminum engines and radiators. Do not use aftermarket coolant reinforcement agents, sealers and/or flushing agents as those chemicals could corrode aluminum parts, or cause clogging.
Genuine Subaru Cooling System Conditioner improves the efficiency of the cooling system and includes anti-corrosive properties. When used as directed, it remains suspended in the radiator until the engine is started and thermostat fully opens.
Once the conditioner begins to circulate throughout the cooling system, it is attracted to any suspected leakage area in the vehicle’s cooling system. The heat generated by the engine acts as an activation agent and hardens the cooling system conditioner to help seal the area. Subaru of America, Inc. has determined that this product is safe for use in all Subaru vehicles.
Genuine Subaru Cooling System Conditioner must be completely used, once the bottle is opened. Exposure to air can compromise its effectiveness. If you find the seal on a bottle removed, opened or damaged when the cap is removed, do not use that bottle of conditioner.
Note: Thoroughly inspect the cooling system before adding the conditioner. Conditioner does not remedy concerns where coolant is found in the combustion chamber, loose heater hose clamps, or cracked coolant reservoir tanks. Be sure to properly diagnose the cooling system before deciding to use this product.