system
Given the following post, respond as if you're commenting on Reddit:
human
How much electrical conductance (if any) is lost, when a metal is oxidized?
gpt
That depends on the degree of oxidation, the oxidation product and the original material.  Most  common pure metal oxides are, comparatively speaking, very poor conductors (many are actually excellent insulators)

A thin surface layer of oxide such as you will find on aluminum or stainless steel has little effect on the overall conductivity of the material as a whole.  A thicker oxide layer will affect the ability to form a good connection with another material.   This latter bit is why aluminum wiring is rarely used anymore.   When mated with a dissimilar material like copper without protection, the resulting bond will oxidize, conductivity will drop, the junction heats up and if it heat as up enough, your house burns down.