"DOT 5 is for silicone brake fluid. Silicone brake fluid (DOT 5) should be avoided because it is not compatible with regular brake fluid, it is hard to pour without introducing bubbles and thus results in soft pedal feel, and moisture still gets into your system and will pool in low areas like your calipers and encourage rapid corrosion. STAY AWAY!"

This ignores a major factor: Silicones are NOT hygroscopic like glycols (which
are a sugarlike, in fact syruplike) material both in properties and in chemical structure. Silicones are more like an oil, so there is no driving force either to attract or entrain moisture. I have used silicone brake fluids in one of the most humid environments in the world (where hydraulic brake systems were notorious for water contamination and subsequent corrosion, usually within a year or two) and not seen ANY water in any DOT 5-filled system.

I point out that the FAQ is for late-model Volvos, such as 700 and 900 series,
and probably by extension other late models like the 240s. I have never had one of these. I am, by education and experience, and also by registration,
(although now allowed to expire since my retirement) a professional engineer specializing in corrosion, materials deterioration and mechanical failure analysis. I was involved in testing Silicone brake fluids in Panama under the authority of the US Army Tank - Automotive Command, which is located in Warren, Michigan. They had then, and continue to have now, engineers who are highly specialized in automotive systems, and they studied this issue carefully at the time they began to consider using Silicone fluids in military vehicles, and likewise through the adoption phase. The adoption of Silicone brake fluids in military vehicles tremendously reduced the problems with water entrainment and subsequent corrosion and destruction of brake cylinders, seals, etc in vehicles from jeeps through military trucks. Based on this I elected to try DOT 5 brake fluid in my 122 after both the master cylinders (brake and clutch) were seriously damaged by corrosion, along with some wheel cylinders. I started converting over in 1984 and used the vehicles in Panama until my departure in 1998, and in Oklahoma (noted for nasty winters and humid summers) from then until now. In summary, I have had no problems that I could relate to the DOT 5 fluid, and the few times I have had brake components apart I have specifically looked for moisture at the bottoms of the components. I didn't find any moisture. I have had one clutch master cylinder fail by normal wear after 15 years of continuous use. I think that is pretty good.

I challenge those who say that "they may not be used in Volvo cars without major brake system modifications" to state exactly what those modifications are.
I believe in the oldtimers, no modifications are necessary. In fact the old problem with brake lines swelling shut and acting like check valves might very well not occur with silicone brake fluid.

If there ARE real, and nonpreventable problems with silicone brake fluid, let's
publicize them, not just refer to them as 3rd or 4th person hearsay. That is the kind of dogma that kept doctors from being required to wash their hands after autopsies for hundreds of years!

Yours for rational discussion based on fact,

--
George Downs, Bartlesville, Oklahoma, Central US