Little grease is needed but it wouldn't hurt to try. You can use almost anything but white lithium seems to be preferred. To answer your question regarding the fans, heat is the enemy of electronics. A fan on the board and X-motor helps prolong their life. Without additional cooling it would seem as though their lifespan is roughly 1.5 years 
Printit Industries Model 8.10 fully enclosed CoreXY, Chamber heat
3-SD3's & a Workbench all fully enclosed, RH-Slic3r Win7pro, E3D V6, Volcano & Cyclops Hot End
SSR/500W AC Heated Glass Bed, Linear bearings on SS rods. Direct Drive Y-axis, BulldogXL
Thanks to all for your contributions