I wash my darling Prius weekly, and there are these stubborn caked-on water spots stuck on the large right-side passenger wiper arm motor thing. No matter how much I scrub or wash, they won't come out. Does anyone have any suggestions?
On my previous car (Camry) those black wiper arms also fade over the years, and look crappy. I waxed mine a few times, but it didn't seem to prevent the fading. But I never had any water spots on them.
Are they for 100% certain water spots or could they be wax stains on the large black plastic cover on the base of one of the wipers? Sounds like from what I bolded above you are talking that plastic cover and not the wiper arm itself which leads me to think maybe it is dried on wax/polish and not water spots. If so, you need something like this: Mothers Back to Black Heavy Duty Trim Cleaner, best car wax remover plastic trim And hey, maybe even if they are somehow water spots, this stuff may get em' off for you. Just realize this is for plastic trim, I wouldn't use it on the wiper arms if in fact that's where you're talking the spots are.
After you have completely cleaned the car, get a teri towel and spray WD-40 on it and wipe it on the affected area. That should do it.