Ok, the fools here in my city throw salt around like it's water, and 3 days after washing my damn car of the salt on the one day it was above 33 F, we had another slight snowfall and they did it again, and my car is covered in salt -again-. I haven't had the opportunity to wash it off yet, and it's been about a week. How corrosive is this stuff? How soon should I be trying to wash it off?