To make sure that your print head and Z stage can move smoothly at all times, it is advised to lubricate the axles every month after the first year of printing. If the axles feel dry, this can show in your prints as small ridges on surfaces. Apply some oil to the axles at least once a month.
A bottle of oil is included in the accessory box of your Ultimaker S5. This oil is specifically for the smooth axles of the Ultimaker S5. Only use the supplied oil, as using other oils or grease may affect the coating of the axles, which can affect the performance of your Ultimaker S5.
X and Y axles
Apply a small drop of oil to each of the X and Y axles as well as both print head shafts. Manually move the print head around to evenly distribute the oil.
Caution: Do not apply too much oil to the axles, as it might drip from the axles on to the build plate, which will affect print adhesion. If a drop of oil does fall on the build plate, make sure to clean it thoroughly before printing.
Apply a small drop of oil to each of the Z axles. In the Ultimaker menu, go to Configuration > Build plate. Select Raise and then Lower to move the build plate up and down in order to evenly distribute the oil.