ΔE 18.0, loose: different enough that you should pick on purpose. Mithril is noticeably lighter, more muted than Oily Steel.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Mithril is noticeably lighter, more muted than Oily Steel.
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.
See Oily Steel on the colour wheel See Mithril on the colour wheel
All matches: Oily Steel equivalents · Mithril equivalents