On Tuesday, February 24, 2015 at 1:37:03 PM UTC-5, Fester Bestertester wrote:
There are some members of electronic forums that suggest coating automotive
battery posts with grease ("any king--axle, lithium, copper") before
attaching cable-end clamps to the posts and swear that it doesn't affect the
connection adversely.

I've always understood it to be that any grease you apply will not interfere with the contact of the metals which occur at the molecular level. Any grease not squeezed out will occupy the space that air and moisture would occupy otherwise.

I've always put a thin coating of dielectric grease between the post and terminal, and have never had a bad connection at a battery since. If there is any interference by the grease, it must be offset by the terminals remaining free from oxidation.