Parts for your 2004 Subaru Impreza-Transmission fluid

2004 Subaru Impreza transmission fluid — what it does and when to change it

Transmission fluid is absolutely relevant to a 2004 Subaru Impreza. Subaru’s 2004 Impreza Owner’s Manual and service literature specify automatic transmission fluid (ATF) for models fitted with the 4EAT automatic, and API GL-5 75W–90 gear oil for 5‑speed manuals (often referred to in Subaru documents as Extra S). Those technical sources make it clear the car needs the correct transmission lubricant to operate as intended.

Whether it’s an auto or a manual, the fluid’s job is to protect and keep things moving smoothly. In an automatic, ATF also acts as a hydraulic fluid to engage clutches and bands, cools the unit, and manages friction so shifts feel right. In a manual gearbox, quality gear oil cushions gears, protects bearings and synchros, and keeps shift feel crisp, especially when cold.

• Reduces wear by forming a protective film on gears and bearings
• Controls heat and carries contaminants to the filter or drain point
• Maintains proper shift quality and noise/vibration control

Recommended specs: 4EAT automatic uses ATF meeting Dexron III (many Subaru service updates allow Subaru ATF-HP where specified)