8 mm PLA Linear Bushings LM8UU LM8LUU

UPDATE 3 (regarding Wanhao Duplicator i3/i3Plus):
I can only recommend removing the bearing rods and abundantly grease the inside radius of the original linear ball bearings with MoS2 grease, and remounting the bearing rods again with the greased original linear ball bearings. I have tried more than one type of printed bushings and they are not up to par with the original linear ball bearings when the original linear ball bearings are greased properly. The greased linear ball bearings are quiet