Can I just paint over rust with Rust-Oleum?

You can paint over rust with Rust-Oleum, but you should not just paint directly over heavy loose rust without preparation, as paint will fail sooner if you skip prep steps. Rust-Oleum makes specific products designed to go directly over lightly rusted surfaces, such as Rust-Oleum Rust Reformer, which chemically converts rust into black paintable surface, and Rust-Oleum Rusty Metal Primer, which is formulated to penetrate rust and stop it, allowing topcoat to adhere. For best results when painting over rust, first remove loose rust flakes, scale, and dirt using wire brush, sandpaper, or wire wheel on drill until surface is as smooth as possible and only tightly adhered rust remains. Then clean surface with degreaser or mineral spirits to remove oil. Then apply Rust Reformer or Rusty Metal Primer according to label, allowing dry time. Then apply two coats of Rust-Oleum Protective Enamel topcoat for barrier protection. If you just spray regular Rust-Oleum paint over thick flaking rust without removing loose rust, paint will trap moisture and rust will continue underneath, causing peeling within months. Light surface rust can be painted over with Rust-Oleum directly after light sanding. For heavy rust, use converter first. Also fix water source causing rust, like leaking gutters, to prevent recurrence. So yes you can paint over rust with Rust-Oleum if you use correct rusty metal products and remove loose rust first.