As Ange said DOT5 is silicone based and not compatible with other fluids. But there's another more important reason not to use it. All the other DOT fluids are hygroscopic, which means they absorb water moisture. This might sound like a bad thing, but it's not.

The silicone based fluid doesn't absorb water, so the water allowed to pool in low areas in the system, which means it can cause rust in those areas.

Your supposed to change brake fluid once a year anyway, so the water will come out, but a year is long enough for rust to occur and damage stuff...