chuckparker said:
Because they get a commission.
It voids your factory warranty and then (supposedly) the rust proofing company gives you a "better" warranty.
I'll take a factory warranty thanks anyway. I'd rather argue with Ford, or Toyota, or GM than argue with Ziebart, or Krown, or whoever applies that goo.
Look at it this way, in 7 years, your car is basically worth a fraction of what you paid for it in the first place. It won't rust out in the first 5 years. So, if it rusts out by 7 or 8 years, who cares, it's a shit box by that age anyway and no-one wants it.
New cars are put through a very high tech painting and corrosion inhibiting process, including dunking the entire body into a tank where the paint is charged with one polarity and the body with the other. It's a water paint process and it's called Electro Coat Paint Operation, or ELPO for short.
Following that, the car is is given 2 other rust inhibiting primers, then it is final coated.
Rust proofing is generally some loogin drilling holes in your B post and C post and shoving some wand in there and coating it with one goo or another which will cause the dirt to stick, plug the drain holes and do very little to prevent corrosion.
