I live where the roads get a combination of sand and salt sometimes brine in the winter. I am considering buying Fluid Film to spray onto the 200 Series, and heard this is a good product to reduce the spread of rust. Does the fluid film coating just get washed off with the next several undercarriage car washes? Thoughts on how to best tackle the rust dilemma? Thank you, I get it there's not simple solution, just looking to see what others are doing.