WD40 is good (as is GT85) but you obviously have to use the right product for the right application. As a rule of thumb...
GT85/WD40 for bike chains, dispersing water and for applications where there isn't heavy frictional contact (otherwise it just wears off).
Moly grease for CV joints / wheel bearings
Copper slip for bolt threads, contact faces (ie. wheel > hub to stop it sticking on) ...
Standard grease for movey bits, door hinges etc.
Lithium grease for wheel bearings and high heat applications
