Applying silicone grease to plug boot

One caveat----not all "dielectric grease" is silicone based. I used to service HVAC, and although I'm not an electrician, certainly was "into" some of this stuff. The greas you get---for example---commonly used in electrics for things like aluminum wire connections is NOT commonly silicone. I would be a little concerned that "some other" material would damage silicone wire insulation.

First time I saw grease used in auto applications was the "Trucklite" sealed tail lamp assembies, and of course now all the manufacturers use it in their connectors.