Dont waste your money... It's oxymoronic to require drilling a pilot hole (which will be the main reason why your factory sealed car can get rusted) to apply rustproofing.
Understand that most will not honor the warranty if the car has been into an accident, which, in most cases, rustproofed or not, if the factory rustproofing and primer is exposed to air and moisture, it will rust.
sa palagay ko mas maganda mag pa undercoat/ rust proofing lalo na kung dadaan ka sa baha na may alat/ chemical etc. like sa malabon, roxas blvd. malapit sa dagat at di nakakakahiya pag benenta mo sasakyan mo na may kalawang sa ilalim o bulok na o nabulok agad sa kanila after a year,
what i did was bought a 1 gallon 3m undercoat at a store in banawe 1.2k ata, and then used a paint brush to apply it.... puro ko ipinahid, walang dilution... mas maganda dahil ang kapal, covered lahat lahat talaga... tiisin mo nga lang mag brush, pero it will last, last really long...sobra sobra pa 1 gallon sa isang suv... malalagyan mo lahat wheel area and your chassis and other exposed metals.