[FWB]

well the kero did require elbow grease i remember getting a new lathe that was dipped in cosmoline i scrubbed that baby for a week.
i was a little scared to use anything on my cast aluminum valve covers, they took too long to get and were not a cheap date. so the wd was my juice of choice. maybe the moisture did have salt in it and its now etched. no salt in the air here so i may have an easier time than you.