To make sure that your print head and Z stage can move smoothly at all times, it is advised to lubricate the axles periodically. 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 machine oil is included in the Accessory Box of your Ultimaker 3. This oil is specifically for the smooth axles of the Ultimaker 3. Only use the supplied machine oil, as using other oils or Magnalube may affect the coating of the axles, which can affect the performance of your Ultimaker 3.
X and Y axles
Apply a small drop of machine oil to each of the X and Y axles as well as both print head shafts. Manually move the print head around to equally distribute the oil.
Caution: Do not apply too much oil to the axles, as it might drip from the axles onto the glass plate, which will affect print adhesion. If a drop of oil does fall on the glass, make sure to clean it thoroughly before printing.
Apply a small drop of machine oil to each of the Z axles. In the Ultimaker menu, go to System > Build plate. Select “Raise” and then “Lower” to move the build plate up and down in order to equally distribute the oil.