Wow, what a systematic approach and huge amounts of patience! Nice job.
It sure seems that the greased lugs played a part in eliminating the squeak. There are people more qualified to write on this so I'll just bring up one related topic: There seems to be a general engineering agreement that a lubricated bolt/nut will yield more clamping force with the same torque setting than an unlubricated bolt/nut at the same torque setting. So perhaps the squeak disappeared because the wheels were on reeeeeal tight?
In other words, even at identical torque wrench settings, a lubed bolt will hold the wheel tighter than a dry bolt, but this over-torquing might also stretch the bolt.
One of the reasons many people don't over-torque their wheels is that they do not want to put so much strain on the bolt that it deforms. Imagine a rod made of playdough--as you stretch it, the center portion will get skinnier. A metal bolt acts the same (but obviously it takes much more to stretch it). And when the center threads get thinner (even if just a bit), it will then be easier for the bolt or outer threads to work themself loose.
A ton of info can be found on Google, here's three to start:
And here are some pictures to illustrate (not all are wheel bolts):
And just to counterpoint myself, I've read that lot of people do lube their bolts without problems.
I'm not drawing any conclusions, just adding to the discussion. And I certainly appreciate
's impressive data logging.