[Pigeon Roost]

Mixing DOT three with DOT four results in a factor determined by [the square root of (the square of three plus the square of four)]. Thus five. Didnya guys learn noth'n in algebra class?

Seriously, there may be no chemical disagreement; but why do that? Unless you have a leak, there is no reason to top-up brake fluid and a very good reason not to.

prs