ΔE 13.8, fair: the same colour family, but not a straight swap. Dark Umber is a little darker, more saturated, warmer than Oak Brown.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Dark Umber is a little darker, more saturated, warmer than Oak Brown.
The same difference applies the other way round: Oak Brown is a little lighter, 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 Oak Brown on the colour wheel See Dark Umber on the colour wheel
All matches: Oak Brown equivalents · Dark Umber equivalents