1999 Subaru Impreza Owner's Manual - Page 268

SAE viscosity number and applicable temperature OM-H2756 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 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 Cooling system, hoses and connections Your vehicle employs an electric cooling fan which is thermostatically controlled to operate when the engine coolant reaches a specific temperature. If the radiator cooling fan does not operate even when the engine coolant temperature gauge exceeds the normal operating range, the circuit of the cooling fan may be defective. Check the fuse and replace it if necessary. If the fuse is not blown, have the cooling system checked by your SUBARU dealer. If frequent addition of coolant is necessary, there may be a leak in the engine cooling system. It is recommended that the cooling system and connections be checked for leaks, damage, or looseness. 10-12