Dialectric grease is an insulator. I don't think it's advisable to dip the wires in it before crimping. Squeezing it in afterward may be helpful except if you have adhesive lined heat shrink, in which case it seems like it would prevent a good bond.I have added dipping the end of the wire into dielectric (silicon) grease or squeezing a small amount into each end of the crimp / splice; on the notion that it keeps water and corrosion out as a secondary defense; in addition to the other good ideas before this. It's easy and quick-may do nothing more than make me feel better?
Does anyone use a "conductive" grease in their crimps? This is a link to the one sold by sailors solution:Dielectric grease (which is an insulator as posted above) adds nothing to a good crimp done properly with heatshrink.