Originally Posted by Z K
I would not do this. WD40 is a lubricant, not a dressing or a cleaner. It will just leave everything greasy and wet looking under the hood.
do you know from experience? It is a cleaner also
As I said I been using it for many, many years, and you must spray and wipe it off.
Most actually evaporates due to its chemical composition leaving a little film (the mineral spirits/oil) behind.
Works very, very well. Sure they make other products also, but this is def a good one for this purpose.
edit: from WD 40 site: cleans and protects engine bay