2002 Subaru Impreza Owner's Manual - Page 321

Maintenance and service Cooling system WARNING 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. HGB032BB SAE viscosity number and applicable temperature 1) 5W-30, SAE 5W-30 preferred 2) 10W-30, 10W-40 CAUTION D 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. - CONTINUED - J Recommended grade and viscosity under severe driving conditions If the vehicle is used in desert areas, in areas with very high temperatures, or used for heavy-duty applications such as a towing a trailer, use of oil with the following grade and viscosities is recommended. API classification SJ or SH: SAE viscosity No.: 30, 40, 10W-50, 20W-40, 20W-50 11-13