Field Grey Shadow FS-34086 vs US Olive Drab

How close are they?

ΔE 6.1, close: similar, with a visible difference side by side. US Olive Drab is warmer than Field Grey Shadow FS-34086.

Can I use US Olive Drab instead of Field Grey Shadow FS-34086?

Usually, if you are not matching paint already on the model. Close match (ΔE 6). US Olive Drab is warmer than Field Grey Shadow FS-34086.

Can I use Field Grey Shadow FS-34086 instead of US Olive Drab?

The same difference applies the other way round: Field Grey Shadow FS-34086 is 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.