Hang it. Warping is the real enemy.

Hang the guide bar vertically, but first wipe it clean and coat the rails with a thin layer of oil. That covers both the rust and the shape problem.

Lying flat is fine if it’s on a flat surface with nothing stacked on it. But hanging avoids any chance of the bar taking a set from uneven pressure, and it keeps the tail end stress-free. Warping is the bigger long-term issue here because a bent bar ruins cuts and wears your chain unevenly.

The oil-soaked cloth thing is mostly old wives’ tale. A light oil film on the bar itself will stop corrosion just fine. Wrapping it in a soaked rag can actually trap moisture against the metal and make rust worse, especially if the cloth is touching the groove. Clean the bar with a scraper, give the groove and rails a thin coat of chain oil, then hang.

Don’t obsess over “edge corrosion.” The edge isn’t the cutting part — the chain is. You’re protecting the rails, and a simple wipe of oil does the job.

Future you with a straight bar says thanks.