[alfa] brake fluid and rust

[C M Smith <cmsmith@xxxxxxxxxxxxxxx>]

It should be clear that water does not cause rust, only oxygen can cause rust.

Damp causes rust because of electrolytic action. Water holds salts in 
solution which facilitate the oxidation of mild steel, but only in the 
presence of oxygen. That's the main problem with surface corrosion of steel 
bodywork in winter where salts are used for ice melting.

Water in brake fluid is a problem because of boiling point issues, not 
rust. While water can hold dissolved oxygen I doubt the water absorbed in 
brake fluid can. It is the water molecules that the brake fluid attracts 
out of the air. Whether oxygen will dissolve better in silicone brake fluid 
or conventional fluid would be the issue, not water.

Brake fluids are hygroscopic, water attracting, not necessarily air 
attracting. Clearly any air in brake fluid would have to remain dissolved 
or non existent, those would be the only options, or the hydraulics simply 
wouldn't work. I think brake fluid will not dissolve air.

Cheers


Michael Smith
White 1991 164L
Original owner
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