There are five spots which can benefit from occasional lubrication: the bottom of the threaded Z rod, and around the bushings on each of the four steel rods (two rods for the build plate shuttle, and two rods for the gantry); see Figure B.1. We recommend Tri-Flow lubricant (often used on bicycle chains), which is a “dry” lubricant. Put a drop of the lubricant at the bottom of the threaded Z rod, and a drop both in front of and behind each bushing on each rod.
In addition, if you are hearing any squeaking from the printer, you may wish to apply a drop of lubricant at the top of the threaded Z rod, and on the drive pinion.
For a video demonstration see: