Oily Steel vs Rust (Metallic)

How close are they?

ΔE 26.2, loose: different enough that you should pick on purpose. Rust (Metallic) is noticeably lighter, more muted than Oily Steel.

Can I use Rust (Metallic) instead of Oily Steel?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 26). Rust (Metallic) is noticeably lighter, more muted than Oily Steel.

Can I use Oily Steel instead of Rust (Metallic)?

The same difference applies the other way round: Oily Steel is noticeably darker, more saturated.

ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.