One of the world's foremost saxophonists and educators, George Garzone (USA) at The Music Place South Melbourne recently.
Simply place a drop of Key Oil on every moving part, on or into the rods and pivot screws, basically everywhere that there are moving mechanisms that have two parts rubbing together. Work the oil in by playing or moving all the keys.
Once every three months or so, depending on how much playing you are doing. It is usually possible to see, feel, or hear when the mechanism is running dry. When you get your instrument serviced (ideally every 12 months [link to why service page]) the technician will clean off the old oil and replace it with new oil. Most oils are spirit or petroleum based and will thin out over a period – losing their lubricating quality. Mechanisms will wear really quickly if they are not lubricated so it is really important to make sure that you keep on top of this task.