ΔE 19.1, loose: different enough that you should pick on purpose. Rus. AF Grey Prot. Coat is noticeably lighter, warmer than Frost Blue.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Rus. AF Grey Prot. Coat is noticeably lighter, warmer than Frost Blue.
The same difference applies the other way round: Frost Blue is noticeably darker, 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 Frost Blue on the colour wheel See Rus. AF Grey Prot. Coat on the colour wheel
All matches: Frost Blue equivalents · Rus. AF Grey Prot. Coat equivalents