2004 Subaru Impreza Owner's Manual - Page 416

Maintenance and service Automatic transmission fluid ! Checking the fluid level The automatic transmission fluid expands largely as its temperature rises; the fluid level differs according to fluid temperature. Therefore, there are two different scales for checking the level of hot fluid and cold fluid on the dipstick. Though the fluid level can be checked without warming up the fluid on the "COLD" range, we recommend checking the fluid level when the fluid is at operating temperature. ! Checking the fluid level when the fluid is hot 1. Drive the vehicle several miles to raise the temperature of the transmission fluid up to normal operating temperature; 158 to 176°F (70 to 80°C) is normal. 2. Park the vehicle on a level surface and set the parking brake. 3. First shift the selector lever in each position. Then shift it in the "P" position, and run the engine at idling speed. 1) Yellow handle 1 HGB056JB - CONTINUED - 11-31