I was cleaning the roof vent fans on my 1998 Holiday Rambler Navigator and found grim smudges of some sort. Water isnt taking them out at all. Any suggestions?
Rubbing alcohol would be the strongest I would go. Stuff like goof-off or the like will start to melt the plastic. No good. You might try windex, first.
If cleaning materials don't work, try Tilex. Just spray enough to wet the surface, but not drip - don't scrub or wipe it off. Let it dry and see if it fades in a couple days. It may be a mildew stain.