unless it's contact cleaner, for cleaning contacts. Folk are so used (conditioned..?) to thinking of WD40 as a rust remover et al, it's not (yet...) in the Public Psyché to imagine that they do, now, make a contact cleaner. It's so easy, though, to reach for the wrong can; I use KF2 (I'm in France...), or Kontact. Both are very good; WD40 may well be, but my can lasts so long, I may never get to try it out.