I don't think I would use dielectric grease per say, but I wouldn't have any problem using something like the T&B inhibitor. It's a black grease like product that is made specifically for both copper and aluminum wires.
Some people swear that dielectric grease will be dispersed when the conductors are torqued in the lugs, but I personally wouldn't feel comfortable believing that it makes a solid, low resistance connection unless the manufacturer specifically says it is okay for that application.
These days I mostly use dielectric grease on things like battery terminals after the connections have already been made up and on the lip of spark plug boots to seal out moisture and prevent them from sticking to the plug insulators. Along time ago, we used it for sliding the rubber sleeves on primary load breaks, etc., but I haven't even been around anyone that does that type of work for years.
