[Vwdiesel] Silicone Brake Fluid

[William J Toensing]

Has anyone had any experience positive or negative with the use of DOT 5 Silicone Brake Fluid in our VW & Mercedes diesels? When I acquired my low mileage 1941 Ford 25 years ago the OEM brake hoses & rubber components were shot so I replaced the master & wheel cylinders together with new rubber brake hoses all around 25 years ago, & no problems with leaking since. I still have the car which now has around 33,000 miles on it. The advantage of silicon fluid is it is non-hydroscopic whereas DOT 3 & 4 brake fluid is hydroscopic attracting water & thus rust in the brake system. I am told to successfully use DOT 5 silicon fluid you MUST replace all rubber components that have ever came in contact with DOT 3 & 4 fluid to prevent water from eventually seeping into the brake system & causing rust. I also have used DOT 5 silicon fluid in my Model A which was converted to hydraulic brakes about 15 years ago & no problems. I did convert a 1965 Olds & 1960 Panhard  PL-17 (both since sold) to Dot 5 silicon & no problems while I owned them. However, I did have rust problems with the rear wheel cylinders on my 1955 Packard & 1954 Hudson Hornet (for sale) but I think problems were due to not replacing all rubber brake components in the Hudson & Packard. The only problems I have noticed with DOT 5 (note: all DOT 5 is silicon fluid) is it seems to cause the brake light switches to stop functioning after a few years. As I recall, both VW & Mercedes recommend against the use of DOT 5 silicon fluid.
Bill Toensing, Nevada City, CA.