Originally Posted By: Ursae_Majoris
Vaseline/petroleum jelly works great on battery terminals too; and it is cheaper than terminal grease.
Correct me if I am wrong, but dielectric grease is not what want on the batter terminals, since it impedes the current flow. It is used to insulate the connectors, like spark plug boots. You want actual battery terminal grease, or petroleum jelly---same thing.
I've kept battery terminals clean and corrosion-free with Vaseline since the 70's. It works just fine.
Technically, anything that doesn't conduct electricity is a "dielectric", so Vaseline or any of the spray on products (WD-40 for instance) are "dielectrics".
What's important for this application is the "grease" part of "dielectric grease" - it keeps moisture and sulfuric acid fumes from the battery vents out of contact with the metal terminal and clamp and prevents corrosion.