Maintenance: Subaru Periodic Vehicle Maintenance Services:
Engine Cooling System and Engine Coolant:
Engine coolant should be replaced at 30 month or 30,000 mile intervals. Check the condition of the hoses and other cooling system components during every scheduled maintenance visit. Check for cracked or otherwise damaged cooling systems hoses, as well as any signs of coolant leakage. A cooling system pressure test will confirm the integrity of the cooling system and radiator cap. A radiator hydrometer can be used to test the antifreeze concentration of the coolant.
Subaru recommends the use of Subaru Genuine Coolant in Subaru vehicles. This recommended coolant contains antifreeze and anti-rust agents that are specially made for Subaru engines, which feature aluminum crankcases. Other coolant types may cause internal engine or cooling system corrosion.
Some Subaru vehicles feature an air breather plug in the radiator, which can be used to remove trapped air during a coolant change. After refilling the cooling system with a 50/50 mixture of coolant and clean water, run the engine long enough to circulate the coolant and to assure that all the air has been removed from the cooling system. The radiator overflow bottle must be filled to the proper level as a final step.