I have used dielectric grease on the contact area of battery wire terminals and battery posts with no adverse effect. It is said by some to be an insulator. Maybe it is until the grease is squished out upon tightening of the fastener, thereby resulting in metal-to-metal contact. And at the same time provides corrosion protection of the connection.
Carl

1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission