The way to stop corrosion on unpainted
engine metal
parts in the pics is clean them,
oil free, and buy Varathane in a spray can. It's plastic and last a long time. Best done when the parts are new.
In the
navy, the guys got tired of daily shining all the brass every day, so polished it one last time, wiped down with acetone, and sprayed it. Lasted forever. Nobody knew except the former polishers and me.