We had this special lubricant manufactured specifically for the plugs and sockets on metal detectors. This lubricant stops most of the friction that can occur when changing coils. The changing of coils causes wear on the critical gold plating in the coil plug and detector socket. If this gold plating wears away the detector will suffer from increased noise and stability issues.
All that is needed is a small amount placed into the coil plug and then connect to the detector. The lubricant stays on the pins until the coil connector is removed where the lubricant evaporates so that the connections will not pick up dirt or have dirt stick to the contacts. This greatly reduces and chance of having any abrasive grit sticking onto the plug and socket pins. The end result is that the connectors will retain the gold plating for much longer and the detector will remain quieter and stabile with reduced contact noise.