Dielectric grease
If put on before you connect the wires. . . .
Yes. Exactly
Dielectric grease promotes conductivity and seals
out harmful moisture.
Some years ago when Fords used EEC IV ignition,
the ignition module included a small squeeze packet
of Ford Dielectric Grease to smear on the contact
points of the module and distributor. The Ford
spark plug wires also had a packet to coat the
ends that went on the plugs and distributor cap
terminals.
I'm fairly sure GM did the same, although I never
worked for a GM dealership.
There's a good many aerosol battery terminal
coatings that work well that dry semi tacky
and keep the cooties away.
I've used Corrosion Block spray on my boat
batteries with good results
Lots of ways to get there
Good Luck