ΔE 11.3, fair: the same colour family, but not a straight swap. Olive Grey is a little darker, more muted, cooler than Bastion Grey.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Olive Grey is a little darker, more muted, cooler than Bastion Grey.
The same difference applies the other way round: Bastion Grey is a little lighter, more saturated, 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 Bastion Grey on the colour wheel See Olive Grey on the colour wheel
All matches: Bastion Grey equivalents · Olive Grey equivalents