Well I was reading more on the website for corrosion free, and here are a few things on it
•Terminates rust and corrosion in all metals
•Clean, clear, DRIPFREE - no sticky residue
•Dissolves and neutralizes existing rust and corrosion
•Penetrates the start of new corrosion
•Protects paint from blistering at edge of lapped seams
•Stops electrolysis between dissimilar metals
•Protects UnderBody including brake and fuel lines
•Penetrates deeply and lubricates
•Repels salt water and moisture
•Will not wash off with water
•Heavy Duty gel formula for extended protection
The biggest reason why we use an undercoating up here is that with all that salt you want some kind of barrier between the salt and the metal.
This Corrosion Free stuff sounds to be pretty good, if it does what it says it does.
Here is one thing I found on the FAQ page.
Does Corrosion FREE apply a black undercoating to the bottom of the vehicle?
No, that'* very bad for today'* newer vehicles! Black tar like or waxy coatings are just a 'cover up'. They seal moisture against the metal and in most cases when they flake or peel off, rusty holes appear on the previously coated surface. Because Corrosion FREE product is clear and you can see through it, you know it really works. It makes the underbody look great too.
So YES the traditional oil spray does trap moisture in, but this stuff is designed to pull moisture out, kinda like WD-40 then, hehe.
Only thing is that this stuff is over 100$ to get it done, well to get the whole car done that is, not just the underside.