Everything except DOT 5 will absorb water and corrode cylinder walls after a few years. I change fluid every year in wet Oregon. I use DOT4.
DOT 5 will not take up water and holds the water getting by the seal, at the edge of the fluid. This spot corrodes more quickly. DOT 5 has other problems with gas absorbtion and gives a spongy feel when brakes are worked a lot. Members of our group have had bad racing experience with loss of braking when they needed it most. DOT 5 will not eat paint. Show cars and Harley's use DOT 5.
Roy