In article , "m II" wrote:
WD-40 my be OK for a manually operate contact but not for an electrically
operated contact. We had a guy try it on a bank of relays and the whole
thing seized to halt!

Sure you did. Urban legend. Something you heard from a friend of a friend.

The stuff evaporates and leaves a sticky mess,

Garbage. It does nothing of the kind.

not to
mention where any arcing has occurred the result is pile of sticky carbon
and a flash that burns the contacts beyond usable.

That, of course, is the entirely *normal* result of an electrical arc
*without* WD-40.

A few mechanics have witnessed signs inside the hoods of`vehicles ``USE OF
WD-40 ON THIS ENGINE WILL RESULT AND NOT PAYING THE BILL OR LITIGATION FOR
DAMAGES``

If by "a few" you mean "zero" then this is probably true.