Yes, we had stripped the wires of insulation about 3/4's of an inch and twisted the al & cu wires together tightly. De-ox was then squirted liberally into the nut and then tightly screwed back on.
My question is what happens to the de-ox after the wires get warm/hot from current passing, does the moisture in the grease evaporate, leaving the chemical related to the de-ox coating the wires?
I would expect that it might vary from one kind/brand of anti-ox to another. But there should be some form of liquid or gel coating left on the wire after use, IMHO.
When I say abrading the wire, I do not mean just stripping it. To remove the aluminum oxide layer you need to first coat the wire to keep the layer from re-forming immediately and then use sandpaper, file, or some other technique to break through that oxide layer before you twist the wires together. As a practical matter, no anti-ox can remove the oxide layer just by spreading it on. Your practice can cause all of the current to flow between the wires through the spring instead of directly from wire to wire. One possible result is what you see in the picture in Dennis' post.
Another may be that the connection gets hotter than it should and boils off the anti-ox.
Ideally if you make the connection properly, the resistance should stay low (at first anyway) if you take the wire nut off without separating the wires.
Read the linked pdf in
post #12 in this thread for more authoritative information.
PS: There is a good chance that part or all of your problem with brittle wires is caused by nicking the wire when stripping it. That will provide a high stress point for a crack to start. However the spring wire inside the wire nut can cause a stress riser also.
