Join Date: Apr 2008
Location: Proctor, VT, USA
As Pard points out, you have a misunderstanding about brake fluids. Absorbed water from the air does not separate-out and pool at lower points in the brake components.
The major brands of brake fluids consist of ethylene glycol, polyglycols, silicone ﬂuids, and isobutyl alcohol. These constituents have the same hydrophilic characteristics due to their molecular O–H structure, which easily allows hydrogen bonding with hydromolecules, i.e., water. The hydrogen bonding is based on the O–H bond in the molecular structure, which permits dipole attraction of the other hydromolecules. In other words, the water molecules are chemically bound-up by the brake fluid and can’t separate out.
Further, brake system water content tends to reach a maximum of about 3%, which is readily handled by the corrosion inhibitors in the brake fluid formulation. Since the inhibitors are gradually depleted as they do their job, glycol brake fluid, just like anti-freeze, needs to be changed periodically. Follow Ducati’s change interval recommendations.