Advice on Swap to Dot 5 - New MC

If you flush your brake fluid every couple of years, corrosion isn't an issue.

I use Castrol synthetic fluid (used to be called GTLMA) It's compatible with DOT 3 and 4, so if I have to, I can just pour in regular brake fluid.

It has a higher boiling point than DOT 4, and doesn't absorb moisture as readily. It costs a bit more than regular brake fluid, but not as much as DOT 5.