OK, you made me look it up...
I had previously posted a long response to that, but it seems to have been digested by the board upgrade.
I'll limit it to this, it only covers "noncritical" appications like aircraft, spacecraft, and nuclear weapons.
The tragedy of Apollo 1 may not have happened if the connectors were properly filled with dielectric grease...
That was a lesson learned the absolute hardest way. (that and don't run electrical junk in pure oxygen)
The proprietary blend used below AFAICT is possibly fluorocarbon grease, although PAO oil is in there too, perhaps as an antioxidant. It may also be just a PAO oil in a teflon-powder based thickener.
(There is such a thing as fluorocarbon soap, so ...)
I assure you its absolutely a dielectric compound, none better..
https://www.google.com/search?q=mil-l-8 ... 8&oe=utf-8
http://www.asetsdefense.org/documents/p ... 20Navy.pdf
For most of our more pedestrian uses, silicone grease works absolutely fine, as long as it is a well designed connection with a wiping and spring action. Spade connectors count as long as they are tight.
Ideal use is in a sealed connector, as it wont dry out.
Don't use it on Molex connectors.... In fact, don't use Molex connectors on anything, they suck.
The air and water-tight seal is the goal, Molex connectors have ~no wiping action, and little spring.
Also, don't use it on relays, as at least theoretically silicone oils can outgas and insulate the contacts with silicon dioxide (AKA quartz), and small signal relays usually don't have enough wiping action on the contacts to self clean.
Power relays like you would use in a car usually do, so I don't sweat it.
I don't mount relays where they can get wet as a rule.