For most electrical connections-anything bolted, crimped quick-connects, lightbulb sockets, and common 12-volt plugs-a dielectric grease or spray is the right answer. To apply, coat the contact surfaces and then assemble the connection as usual. The clamping pressure, whether a bolt or simply the pressure between the contact surfaces in most plugs, pushes the grease out of the way, providing a good contact. You should also coat or spray the outside (not on the lightbulb itself; that can cause failure on halogen bulbs). The remaining dielectric serves to seal the contact area from water, oxygen, and galvanic corrosion. It is a must for a boat owner. It stops corrosion from forming.