Volvo Automatic Gearbox Filters Available Here. The transmission is one of the most essential parts of your vehicle, because it transfers power from the engine to the wheels. Without it, your car wouldn't move. Wear from the gearbox can result in metal shavings in the transmission fluid, which an automatic gearbox filter removes. This filter also helps sift out dirt and other particles from the fluid. Keeping the fluid clean from debris allows the gearbox to provide smooth shifting and proper functioning of the transmission. The automatic gearbox filter should be replaced at the interval recommended by the manufacturer, which usually coincides with the service interval at which the transmission fluid is replaced.