Ok, fucking up my previous GN attempt.

I'm pondering the properties of brake fluid. In both cars and motorcycles, brake operation is the major hydraulic system in play.

Brake fluid in both is glycol based, and glycol is hydrophilous, meaning it attracts water molecules.

In motorcycles, after about two years (depending on local humidity), brake fluid will already be 4% H2O, and need to be flushed out and replaced to maintain its high boiling point and compression qualities. Brake failure is obviously quite dangerous on a motorcycle.

But it would also be dangerous in a car, and how often, if ever, are car brake systems flushed to remove all compromised brake fluid? As a driver of a 30+ year-old automobile, and owner of several autos that are 10+ years old, I doubt any of them have had their brake systems flushed. I'm guessing all are running fluid well above 4% H2O.

Flushing attempts to remove all old fluid and replace it with new fluid. While bleeding brakes removes air in the system and is often done when changing pads, calipers, drums, and shoes (really any brake component that involves breaching the hydraulic system and allowing air to enter), bleeding only introduces a small amount of new fluid into the system.

I assume this is why master cylinders, boosters, and other ferrous brake components are subject to failure over time, due to rust buildup. But long before component failure, I would expect other negative effects (boiling, hydro lock, loss of compression and "spongy" reaction) because of H2O-compromised fluid. Maybe some of these failures are mitigated by having a mechanical (cable-actuated) emergency brake system, which motorcycles do not have. Maybe the relative volume of fluid in an automobile is beneficial - relative to the amount of exposure to air or anything else containing H20.

Could water separators be effective? I'm curious if water separators are part of other glycol-based hydraulic systems, or cooling systems dependent on the high boiling point of glycol. If glycol is hydrophilous, how would those separators even work? Certainly much differently than with a hydrophobic fluid.

Any ideas? Yes, this is a little material science, some chemistry, some physics. Not areas I am an expert in. But I have an appreciation for it all the same.

Not my usual philosophy, anthropology, sociology, psychology bent, but interesting all the same.

Ok, GN.