what I learned about DOT 5 silicone based brake fluid. My Dad bought a 1982 244GL and in 1983 I began a two year program in Automotive technologies.( I graduated in 95 with an applied sciences degree in automotive technologies
and went on to work for 30 years as a mechanic. anyway back in 83 at scool I flushed out the brake system on the 244 GL flushed it complettly out with alcohol and blew it dry with air and installed the Dot 5. where it remained until 2003. the DOT 5 brakefluid was all the new rage. it had a higher boiling temp thenthe glycol fluids, but what really made it stand apart was it could not mix with water. while glycols are are knowen as a Hydroscopic fluid meaning the readily combine with water.. the thinking at that time was this would make for a "lifetime fluid" never needing to be to be replaced. Ford jumped on the band wagon for a few years as did the US postal service. ford quietly dropped the the Dot 5, while I know the postal service was still useing it in the early 2000's. the way this turns out is that although water did not mix at all with Dot 5 the moisture in the air still got into the brake system and condenced out.not mixing with the fluid it still beins to acumulate pooling in low spots where ever it finds them pure water and the corrosive oxigen it is made of. even flushing the fluid, wont remove all the water now, it cant mix. and dot 5 was basicly abandoned. . well long story short the 1982 GL was passed on to my brother and then in an unloved state I rescued the unwanted car. I went to task to fixing it up, and then I remembered the dot five fluid, was it still in there- yep. did it save the brake coponants, NO. the brake failier light had been on, the pressure differential warning valve had failed, and one or more calipers where hanging up a little. cuiosity was on, i used a glass beaker to and filled it with the 20 year old Dot 5 fluid. it still had the purple color although not as bright as when it was new, but the fluid for the most part looked remarkably uncontaminated. then down the leeder hose and in to the beaker came globs of nasy looking water filled with junk.. turns out having a hydroscopic fluid was an advanted, be performing a fluid flush every two years you can remove vertualy all the water andall but tyhe heaviest of particulats, and with regular flushes removimg water rather then iy building up corosion and the particulats it creats are vastly diminished.