Because cars are made with metal, and they are exposed to all kinds of weather, rust should be a concern for any car owner or mechanic. The undercarriage of a car, in particular, is one place that rust can take hold. If left unchecked, this rust can eat away at the floor panels, axles, and other integral components. Paint can also deteriorate over time, and as it does, the exposed door panels can begin to rust. There is a big difference, however, between protecting metal elements so that they won't rust and stabilizing rust so that you can paint over it. 

Sealing Out Rust

When you look for a rust sealer, some of the products that you find are meant to protect metal that will be exposed to the elements. When you look for a sealer that will be used on the undercarriage of a car, you need to consider the sort of abuse that the sealer will absorb. While driving, your undercarriage can be exposed to ice, salt, scrapes, rocks, etc. All of these hazards can eat and chip away at the underside of your car. In that some undercarriages are nothing more than bare metal, if you know that you will frequently face wet weather, looking for a sealant that will resist chipping and fight corrosion can help you to get more life from your car. 

Stabilizing Rust

If you have lightly rusted metal, you don't necessarily have to sand away all of the rust away. You can use a rust sealer to stabilize the rust so that it does not continue to eat away at the metal. If you simply paint over rust, it can continue to oxidize, and as it does, it will not only damage the metal, but it can also cause the paint to chip and flake off. Some metal panels will be so badly damaged by rust that you have no choice but to replace them. On the other hand, when you are refurbishing a classic car or just a heavily used car, you can keep costs down by sealing and painting over whichever panels you can. 

Rust, if left unchecked, can eat away at exposed metal until there is nothing left but a pile of brown, orange dust. When you discover rust starting to form on the undercarriage of your car, it is time to act. If your car needs a new paint job, a little foresight and the right rust sealant will help your paint job to last for years to come.