[embee]

"Dielectric grease" is the ideal stuff. Maplins sell it in tubes I think, or look out for Dow Corning DC4 on fleabay, normally rather expensive but comes up occasionally cheap. Honda (and probably other bike brands) do their own stuff but it tends to be overpriced.

You can use "contact cleaner", also available from Maplins, the better version is the type with lubricant included.

ACF50 works well I believe though I don't use it. Vaseline is fine in most circumstances, also works well on battery terminals.