2004 Subaru Impreza Owner's Manual - Page 408

Maintenance and service 7. Put the radiator cap back on and tighten firmly. At this time, make sure that the rubber gasket in the radiator cap is correctly in place. 8. Start and run the engine for more than five minutes at 2,000 to 3,000 rpm. 9. Stop the engine and wait until the coolant cools down (122 to 140°F [50 to 60°C]). If there is any loss of coolant, add coolant to the radiator's filler neck and to the reserve tank's "FULL" level. 10.Put the radiator cap and reservoir cap back on and tighten firmly. Air cleaner element The air cleaner element functions as a filter screen. When the element is perforated or removed, engine wear will be excessive and engine life shortened. The air cleaner element is a viscous type. It is unnecessary to clean or wash the element. Do not operate the engine with the air cleaner element removed. The air cleaner element not only filters intake air but also stops flames if the engine backfires. If the air cleaner element is not installed when the engine backfires, you could be burned. ! Replacing the air cleaner element ! Non-turbo models Replace the air cleaner element according to the maintenance schedule in the "Warranty and Maintenance Booklet". Under extremely dusty conditions, replace it more frequently. It is recommended that you always use genuine SUBARU parts. - CONTINUED - 11-23