Subaru WRX & WRX STI Manuals 2018 WRX & WRX STI Owner’s Manual | Page 482

11-16 Maintenance and service/Cooling system & Synthetic oil You must follow the oil and filter changing intervals shown in the Warranty and Maintenance booklet. NOTE Synthetic oil of the grade and viscosity noted in chapter 12 is the recom- mended engine oil for optimum engine performance. Conventional oil may be used if synthetic oil is unavailable. Cooling system WARNING . Never attempt to remove the radiator cap until the engine has been shut off and has cooled down completely. Since the cool- ant is under pressure, you may suffer serious burns from a spray of boiling hot coolant when the cap is removed. . Be careful of the rotating cooling fan when the engine hood is open. When the engine tempera- ture is high, the cooling fan in the engine compartment may oper- ate when the ignition switch is in the “ON” position, even if the engine is stopped. Touching the cooling fan while it is rotating may result in injury. CAUTION . Vehicles are filled at the factory with SUBARU Super Coolant that does not require the first change for 11 years/137,500 miles (11 years/220,000 km). Do not mix this coolant with any other brand or type of coolant during this period. Mixing with a different coolant will reduce the life of the coolant. Should it be neces- sary to top up the coolant for any reason, use only SUBARU Super Coolant. If the SUBARU Super Coolant is diluted with another brand or type, the maintenance interval is shortened to that of the mixing coolant. . Do not splash the engine coolant over painted parts. The alcohol contained in the engi