ΔE 7.1, close: similar, with a visible difference side by side. Russ. AF Dark Green is a little lighter, more saturated than Petroleum Gray.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). Russ. AF Dark Green is a little lighter, more saturated than Petroleum Gray.
The same difference applies the other way round: Petroleum Gray 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 Petroleum Gray on the colour wheel See Russ. AF Dark Green on the colour wheel
All matches: Petroleum Gray equivalents · Russ. AF Dark Green equivalents