ΔE 10.2, fair: the same colour family, but not a straight swap. Olive Drab is a little darker, more saturated, cooler than Silver Grey No.28.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 10). Olive Drab is a little darker, more saturated, cooler than Silver Grey No.28.
The same difference applies the other way round: Silver Grey No.28 is a little lighter, more muted, warmer.
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 Silver Grey No.28 on the colour wheel See Olive Drab on the colour wheel
All matches: Silver Grey No.28 equivalents · Olive Drab equivalents