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. 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.
Use (sewing) machine oil for lubricating the axles. Other oils or grease may affect the coating of the axles. Sewing machine oil can be acquired from most hardware stores.
Tip: A bottle of machine oil is also included in the Ultimaker 2+ Maintenance Kit.
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.
Note: Do not apply too much oil to the axles, as it might drip from the axles onto the build plate, which will affect print adhesion. If a drop of oil falls on the build plate, clean it thoroughly before printing.
Apply a small drop of oil to each of the Z axles. Move the build plate up and down to evenly distribute the oil. This can be done manually, or via the Maintenance menu: Select Advanced, then Raise build plate / Lower build plate.
Note: Do not apply the oil to the Z motor's lead screw. This must be lubricated with the supplied grease once every three months.