I’m still building my mpcnc but I found on my 3d printer that the white lithium grease is probably not the way to go. I used it liberally after replacing my threaded rod Z axis with leadscrews. After printing a few other things and all the mpcnc parts the grease is no longer white or grey. It’s completely black and looks a little thin. It gets black on me if I accidentally touch it and it’s hard to get off.
I found PB Blaster Dry Lube at Lowes last night and I used it on the threaded rod that I’m using on my mpcnc. the nuts are travelling smoothly on the threaded rod so it seems like it should do the trick. You can also re-apply by spraying it on whenever you want because it’s says it’s safe on plastics.
On a side note, if you ever need lubricant for bearings the best I’ve found is Tri-Flow. Found this out from my time with nitro RC trucks. You can get it at skateboard and bicycle shops usually.