A drive axle assembly drain and refill service is a routine maintenance procedure for a component of the drivetrain system on rear-wheel-drive and four-wheel-drive vehicles.
Each wheel that receives power from the engine - the rear wheels of a rear-wheel-drive vehicle or all four wheels of a four-wheel-drive vehicle - is connected to a large metal tube containing shafts and gears - the drive axle. As the shafts inside the axle rotate, so do the wheels.
To get power to the axle shafts, the transmission turns a drive shaft that runs along the underside of your vehicle. The spinning drive shaft is attached to a gearbox (the differential) located in the drive axle assembly. This gearbox is filled with gear oil that needs to be replaced regularly to ensure proper lubrication and cooling of the drive axle’s internal components. A drive axle assembly drain and fill serves to remove the old fluid and replace it with fresh fluid.
The procedure for a drive axle assembly drain and refill service can vary by vehicle make and model. However, in general, the process is similar to that of an oil change.
A technician will safely raise and support your vehicle in the air for access. A drain plug is removed from the bottom of the axle assembly housing where the gears are located (the differential) and the old fluid is drained and captured. After the fluid has drained out, new fluid is pumped into the housing to the proper fill level.
Some drive axles do not feature a drain plug. Instead, a technician would be required to remove the differential cover plate in order to drain the old fluid. The job becomes more complex and requires other parts, such as a new cover gasket, when this is the case.