I kinda like Fluid Film - basically aerosol lanolin. Farm supply stores (among others) sell it. You can spray it on and wipe it down to a very thin film. It's OK on paint (non staining), but does smell like sheep, which that might be objectionable to some.
Just for fun (and to save $), I've tried making my own. Bought a jar of anhydrous lanolin on Amazon and experimented with several solvents as carriers. It's most soluble in turpentine; WD40 and (cheap) kerosene work almost as well. I keep a jar of the mix on hand, and occasionally wipe it on my machines with a paper towel.
Everything I've heard about WD40 is that it's neither a long term rust preventative treatment nor a good lubricant (at least not by itself). I do use it, usually mixed with lard, for machining aluminum.