Got a 240D, Calif. car. No rust.

Would like to keep it that way. I'm in Utah where they salt the roads in winter.

What's the best way to go for rustproofing?
Can I do-it-myself?

FYI: Called Ziebart. $125 For just undercoat (black stuff).

$330 for "full" rustproofing. Undercoating + yellow gunk sprayed in doors, etc.

No guarantee on used vehicles.