Don’t confuse undercoating with rustproofing.
Undercoating is applied to the underside of a vehicle to deaden vibration and road noise.
Rustproofing is applied to the body cavities of a vehicle to prevent rust
When undercoating is applied, the surfaces must be absolutely clean.
If this isn’t done, the undercoating doesn’t adhere properly to the surfaces creating voids between the undercoating and the vehicle.
These voids accumulate moisture which promotes rust.
And with Krown, you never stop purchasing it.
Solutions such as Rust Check, Krown, or Corrosion Free are applied by professionals every 12 to 18 months at a cost of $100 to $200.
Rustproofing is sprayed into the body cavities with wands thru drilled holes.
Again, the surfaces must be clean for the rustproofing to adhere properly so it doesn’t promote rust.
Undercoating and rustproofing are usually applied when vehicles are new because that’s when everything is pretty much clean.
But automakers advise against doing this because of the reasons above.
And because they feel the rust protection with aluminized and galvanized steel along with the dip process is enough.
And in some cases it voids the corrosion warranty when these processes are done
It’s best to wash and wax the vehicle every six months.
Tester