While in the Navy my boss ordered in what he thought was 2 toothpaste sized tubes of contact grease for installing circuit breakers into switchboards. Turns out they were 8# tubs of the stuff!
I have no idea where one would go to get the stuff here in the "real world," but I'll just hint that when one of the tubs "expired" it made it into a different than usual trash receptical.
It's what I use on lugs and on those pesky Kadett and Manta light bulb sockets that love to corrode away as well.
FWIW, Jeff, when you crimp a lug onto a wire you're counting on the pressure from the crimper to pressure weld the wire to the lug. I'm not sure how warm and cozy I feel about putting grease in there before the actual crimping happens. Afterwards, great, but before, not so great.
If I want a joint to seal up for good, I usually use either heat shrink tubing over the whole thing or liquid electrical tape. Both seal very well, and if the joint needs to come apart later it's just a second with a sharp knife to slice it enough to come apart.