2003 Subaru Forester Owner's Manual - Page 343

Maintenance and service ! 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 towing a trailer, use of oil with the following grade and viscosities is recommended. 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. ! Synthetic oil You can use synthetic engine oil that meets the same requirements given for conventional engine oil. When using synthetic oil, you must use oil of the same classification, viscosity and grade shown in this owner's manual, and must follow the oil and filter changing intervals shown in the maintenance schedule. 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. 11-14