ΔE 16.1, loose: different enough that you should pick on purpose. Petroleum Brown Wash is noticeably lighter, more saturated than Black Tone.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Petroleum Brown Wash is noticeably lighter, more saturated than Black Tone.
The same difference applies the other way round: Black Tone is noticeably darker, more muted.
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 Black Tone on the colour wheel See Petroleum Brown Wash on the colour wheel
All matches: Black Tone equivalents · Petroleum Brown Wash equivalents