FlashForge 5M Guide & Maintanance
Must Do Regurarely
Threaded Rods Noise
There could be times when the bed goes up and down, the threaded rods might make a squeaking noise. This is due to poor lubrication
Apply a decent amount of Lithium Grease

Note: Make sure you remove any excess of Lithium Grease from the Threaded Rod**
Linear Rails (X & Y axis)
Buy the following Sillicon Lubricant the wiki also mentions to use this type of lubricant
Note: the FlashForge Wiki has detailed steps on how to maintain the Linear Rails fully lubricated, check the Wiki Here