Gear oil is used to drive the shaft. It is usually good to change it twice a year. It can be changed to 80W-90 or 85W- 140. You can try Petronas' 85W- 140, which can be used all year round and won't dry the bridge.

Drive axle is generally composed of main reducer, differential, wheel drive and drive axle housing. Its function is to turn the power from the universal transmission device by 90 degrees, change the transmission direction of the force, slow down through the main reducer, increase the torque, and distribute it to the left and right half shafts and driving wheels through the differential.