Dot 4 or Dot 5 Brake Fliud?

I have been using DOT5 for 20+ years without issue.

Things to know:

Not all DOT 5 fluid is of equal quality. As a for instance, parts store brand seems to aerate easily wheras the Cartelbrand we eventually switched to did not.

DOT 5 can crystalize over long periods of downtime. Just like any fluid in you brake system it will need routine maintenance intervals.

The two real benefits of DOT5 are paint protection from spills/leaks and that it's not hydroscopic like DOT3.