You want to deny oxygen and moisture.Most conection terminations are treated for corrosion resistance with a plating. Once you clean one that has evidence of corrosion it is reasonable to assume that protective layer may be gone.

I just normally use thick bearing grease throughout the assembly of electrical terminations. . That way there is not much likelyhood of having to revisit those connections in the future. A silicone grease on connections where there is plastic involved as I would not want to take a chance of the normal grease causing issued with the plastic plugs etc. This all becomes a habit to do with time. Mechanical connections are usually the weakest point in any electical circuit.