Subaru Impreza Manuals 2017 Impreza Owner's Manual | Page 386

11-10 Maintenance and service/Cooling system . If performing oil replacement your- self, observe the local regulations and dispose of waste oil properly. & Recommended grade and viscosity CAUTION Use only engine oil with the recom- mended grade and viscosity. Refer to “Engine oil” F12-4. Warranty and Maintenance booklet. Cooling system NOTE & Safety precautions 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. WARNING Never attempt to remove the radia- tor 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 boil- ing hot coolant when the cap is removed. NOTE Engine oil viscosity (thickness) affects fuel economy. Oils of lower viscosity provide better fuel economy. However, in hot weather, oil of higher viscosity is required to properly lubricate the en- gine. & Synthetic oil You should 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. Refer to “Engine oil” F12-4. Also, you must follow the oil and filter changing intervals shown in the 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). This coolant should not be mixed 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 necessary to top up the coolant for any reason, use only SUBARU Super Coolant. If the SUBARU Super Coolant is