How to maintain the universal joint？

The maintenance of the universal joint cross shaft requires grinding gear oil. Due to the fact that the lubrication nozzle of the universal joint cross shaft needle roller bearing is an ordinary grease nozzle, it creates an illusion for people, and butter has been commonly added for lubrication for a long time. In fact, it is difficult to apply butter to the needle roller bearing from this grease fitting, and even reaching the end face of the cross shaft journal is very difficult. Lubricating with butter (i.e. calcium based grease) can cause early damage to a large number of cross shaft needle roller bearings.