Aluminum & steel don't play well together. Add to that the inconsistancy in the friction in the interface, galling of the surfaces and overcoming the friction of initial install & every time there after...When torquing bolts it's always best to know if it is intended to be lubricated or not...usually it has to do with "set & forget" or if it is a safety critical or field servicable item.
Square taper always fulfilled the safety sensative & field serviceable check boxes for me, so I always have. I've never had a problem & never gave it further thought. For others, maybe their concerns are it never be removed again. Or maybe they are ok not necessarily knowing if they overcame running torque to ensure it actually seated as far as it should. Maybe they feel the chances of galling is minimal, or have little concern for electrolysis, or whatever. Those people don't lube. In the real world, it probably has some oil or grease or something on it that was "left over" & is "good enough" to be ok. The real problems arise out of being truely bare & degreased. We are dealing with the worlds simpelist machine afterall. A speck of grease or not on reassembly is unlikely to cause a real problem either way.
In my field (aviation manufacturing) all fasteners have a specific torque procedure & nearly everything that moves is usually lubricated with grease in some manner. The rest of the structural fasteners are lubricated with cetyl-alcohol. Consistancy of execution is why a friction interface gets lubrication. So I do as I think the engineers at my work would expect.
Last edited by base2; 01-25-19 at 06:07 AM.