I had a lot of underbody work to be done on a car I purchased, where rust was evident on the underbody near the doors on each side of the vehicle. I researched for better methods of treating the rust and decided on Rust Bullet.

I removed layers of rusty metal where needed, removed loose rust on other places and ground the metal outwards from rust areas until I hit solid non rusty metal on all areas to be treated. Rust Bullet claims that it dries out the rust and seals everything and prevents new rust. I normally would have converted what rust was left at this point, but thought I would follow Rust Bullet's recommendations on application to let it "do its thing". I applied two coats.

I then coated Rust Bullet with 3M underbody coating.

I found that Rust Bullet does stick to properly prepared surfaces well.

Now, after two years, I checked the areas, and found some places that were not even, so I checked them. Upon pushing in with a screwdriver, I found that these were bubbled areas of rust. I continued to scrape, hoping that this would be a localized area. The more I scraped, the more I found that the Rust Bullet was sticking very well, but everywhere I removed Rust Bullet, I found a nice uniform layer of rust underneath it. It's sort of like Rust Bullet is sticking to an immediate thin layer of metal below it and maybe keeping that from rusting, but below that the rust continued to form and eat into the metal.

Also, upon application I coated much area that did not have any rust, but now it is all rusty. Rust Bullet did not only *not* stop an existing thin layer of rust, but did not prevent new rust from forming. Due to the amount of rust I am finding, it seems that it started rusting shortly after I applied Rust Bullet.

So, by depending on the claims of this product, my work was wasted and my car is rusting out again.

After I now remove the underbody coating and Rust Bullet, I will removed all loose rust, use a true rust converter, then paint and coat the metal to protect it.

So, I would not recommend Rust Bullet for stopping rust, but would recommend using a true rust converter then properly coating the metal to seal it. Although, if the Rust Bullet I have left in the can is still good, I may use that for the top coat of paint as it does seem to stick well.