Rust proofing: Schutz, cavity wax, other

[apbright]

I am planning to drive my Town Sedan occasionally in winter weather, which will include wet, salted roads. (Yes, call me stupid, but I'm a 42 year old that works on and drives a car twice his age, and it's the snow and salt that makes me stupid?)

I have been trying to read up on 3M Schutz and cavity wax, but don't find much really useful information about what makes sense to put where. Any of you folks have experience good/bad with such materials?

Thanks, Andrew