2005 Subaru Legacy Owner's Manual - Page 517

Maintenance and service API classification SL (or SJ): SAE viscosity No.: 30, 40, 10W-50, 20W-40, 20W-50 Cooling system Never attempt to remove the radiator cap until the engine has been shut off and has cooled down completely. Since the coolant is under pressure, you may suffer serious burns from a spray of boiling hot coolant when the cap is removed. " The cooling system has been filled at the factory with a high quality, corrosion-inhibiting, year-around coolant which provides protection against freezing down to -33°F (-36°C). For adding, use genuine SUBARU coolant or an equivalent: a mixture of 50% soft water and 50% ethylene-glycol basis coolant. Use of improper coolants may result in corrosion in the cooling system. It is important to maintain protection against freezing and corrosion, even if freezing temperatures are not expected. Never mix different kinds of coolant. " Do not splash the engine coolant over paint11-18