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