Q: Can I stop rusting without sanding down and painting my car?

Rust on vehicle sheet metal, and the frame, is extremely difficult to stop once it gets a toehold. To "stop" rust already present on steel, every last minute trace of rust must be removed and then the metal has to be carefully coated with appropriate primers and rust resistant finishes. If the rust is on body panels, the affected section often has to be physically cut out, with new panels welded in. Often the cheapest thing to do is simply buy completely new panels if they are available. Frame damage due to rust can be severe enough to make vehicle restoration impractical and uneconomic expect for exceptionally rare vehicles and/or the dogged determination of the vehicle owner to just never give in. In actual fact, it is rust and not mechanical malfunction that determines the economically useful service life of a vehicle. That, it is relatively easy and economical to replace worn out mechanical components, endlessly frankly, but once a vehicle "frame" essentially "disappears" due to rust you are at the proverbial end of the road. To answer your question, complete rust removal, and thence repainting, is the only thing that works. With regard to the frame, if rust has already compromised the frame, it is usually not worth restoring the sheet metal because the end of lifetime of the frame will be in view. Unless, of course, you want to restore the frame as well and it is not too far gone. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.