ΔE 13.5, fair: the same colour family, but not a straight swap. Old Wood is a little lighter, more saturated than Mud Brown.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Old Wood is a little lighter, more saturated than Mud Brown.
The same difference applies the other way round: Mud Brown is a little 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 Mud Brown on the colour wheel See Old Wood on the colour wheel
All matches: Mud Brown equivalents · Old Wood equivalents