ΔE 17.0, loose: different enough that you should pick on purpose. Beasty Brown is a little lighter, much more saturated, warmer than Petroleum Brown.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Beasty Brown is a little lighter, much more saturated, warmer than Petroleum Brown.
The same difference applies the other way round: Petroleum Brown is a little darker, much more muted, cooler.
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 Petroleum Brown on the colour wheel See Beasty Brown on the colour wheel
All matches: Petroleum Brown equivalents · Beasty Brown equivalents