Subaru Gear Oil Requirements
We recommend the use of normal fluids in the gearbox, not fancy synthetic types. We've had some customers complain of notchy shifting after filling the transmission with synthetic lube.
Fluid recommendations according to Subaru:
Five-speed cars and six-speed cars, including Impreza, Impreza WRX, and Impreza WRX STi; Forester and Legacy:
Transmission: GL-5 or equivalent, 3.5 liters (4.1 liters for six-speed)
Rear differential: GL-5 75W90 or equivalent, 0.8 liters (1.0 liter for STI)
We stock excellent Motul gear lube.