ΔE 10.8, fair: the same colour family, but not a straight swap. Dark Reaper is a little darker, warmer than Ocean Gray (FS35164).
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Dark Reaper is a little darker, warmer than Ocean Gray (FS35164).
The same difference applies the other way round: Ocean Gray (FS35164) is a little lighter, cooler.
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 Ocean Gray (FS35164) on the colour wheel See Dark Reaper on the colour wheel
All matches: Ocean Gray (FS35164) equivalents · Dark Reaper equivalents