What Brake Fluid Should I use?

[Canadasvt]

Installing KVR lines next week. Wondering what brand of brake fluid to use, and DOT 3 or 4?

[David Morton]

If they don't send DOT 5.1 with the kit, get it. DOT 5.1 meets DOT 5 temperature specifications but without the silicone based non-hydromorphic DOT 5 fluiid. It will mix with DOT 3 (which is stock) so flushing it out won't be a problem.

The term hydromorphic means that it will mix with water. Now, seemingly this is a bad thing in brake fluid, water boils at 210 degrees, so if condensation, say on the cap, gets into the fluid it will mix with the fluid and lower the total boiling point of the fluid, right?

Correct, it will. BUT! It's only a few tenths of a degree considering the small amount (one drop in a quart of fluid), and considering the alternative, silicone based fluids, is preferable to having that drop of water go to the bottom of the reservoir and then work it's way down to a caliper where it will boil at 210d when you least expect it, under hard braking.