Hmmm...that is strange...but since I hold the copyright to the article the link was SUPPOSED to be to - I'll simply paste it here. However, I would like to point out that the military test report - and experiments done at my request by a world-class lab matched the army's - that DOT5 can be added to systems filled with DOT3 without trouble - although this does negate any benefit of using silicone.
Here is the info:
TEST REPORT: Silicone Brake Fluid
by David Doyle
Almost everyone in this hobby has an opinion about silicone brake fluid, why the US military uses it, and how to convert a system to it. Unfortunately, there seems to be as much misinformation as there is factual information in circulation about this subject. In May 1966, the US Army Coating and Chemical Laboratory began aggressively looking for a brake fluid that was less sensitive to water than the three fluids in use at that time. The three fluids in use were “Hydraulic Fluid, Polar Type, Automotive Brake, All Weather,” “Preservative Fluid, Automotive Brake System and Components,” and “Brake Fluid, Automotive.”
As their names indicate, each of these had a specific purpose. The first, obviously was used for arctic regions where temperatures were expected in the -30ºC to -55ºC. The second listed was used as a preservative in not only the brake systems of vehicles in long term storage, but also in the packaging of wheel and master cylinders. The last one listed is the “normal” or standard brake fluid.
SILICONE FLUID INTRODUCED
In 1967, various makers of silicone hydraulic fluids became interested in the brake fluid market. Because of the perceived ability to replace three fluids with one, as well as perhaps to address the matter of water sensitivity, the Army Coating and Chemical Laboratory encouraged this development work. Union Carbide, General Electric (GE), and Dow Corning all submitted fluids for evaluation. GE and Union Carbide each submitted two fluids, one each slightly water tolerant (because of the belief that water will somehow enter the brake system), and one each completely intolerant of water. The Dow Corning entry was a water-intolerant fluid.
EXTENSIVE TESTING
Three years of testing by Chemical and Coatings Laboratory found deficiencies with respect to poor lubrication properties and rubber incompatibility. These were mostly overcome by incorporating additives into the various fluids.
When the lab work was done, the Laboratory conducted field tests. Three test locations were selected with widely different weather conditions: Arctic Test Center, Fort Greeley, Alaska, the Yuma Proving Ground, Arizona, and the Tropic Test Center, in the Panama Canal Zone. The results of a one-year test were detailed in Mobility Equipment Research and Development Center Report 2132. The test vehicles for this program at each location were two M151 series vehicles and two M715 1¼-ton trucks. For the testing new wheel and master cylinders were supplied, filled with the various silicone fluids, and new rubber hoses were supplied. The balance of the brake systems were flushed with alcohol prior to the installation of these new components. This trial is quite likely where the trend for alcohol flushing during conversion began.
After one year of service, half of the cylinders in Yuma and Panama were torn down for inspection. Samples of the brake fluid were sent back to the CCL for testing. All the cylinders in the Alaska test were examined. Testing of the Union Carbide and Dow Corning fluids in Alaska were discontinued early because of concerns about crystallization of these fluids under arctic conditions. The GE fluid did not have this problem and both Dow and Union Carbide were able to later correct the deficiencies in their fluids. The cylinders were torn down and inspected for corrosion, pitting and scoring.
The results of these tests demonstrated that the fluids were equal to their predecessors, and in the case of equipment operating in tropic conditions, were superior to the conventional fluids because of less water-induced corrosion in the brake system. The biggest benefit to the military was the anticipated 10 million-dollar annual savings by reducing the number of brake fluids in the supply system from three to one. After extensive testing, the Army published TB 43-0002-87 Brake Fluid, Silicone (BFS) Conversion Procedures for Tank-Automotive Equipment in February 1982.
Whether you are in a tropic area or not, you may choose to convert your vehicle from a conventional brake fluid to a silicone brake fluid. If you convert, remember, do not use air to expel the old fluid from the system. The vaporized brake fluid is extremely flammable.
Silicone brake fluid is completely compatible with elastomer materials used in conventional brake systems. Although it does not mix with conventional-type brake fluids, it is completely compatible with glycol brake fluids as a 2-phase mixture. In other words, an accidental mixing of the two fluids will not cause mutual precipitation or leaching of additives in this type of environment. Thus, the procedure developed for brake fluid conversion is detailed in TB 43-0002-87, February 1982. Essentially, it amounts to opening the bleeders, and with a pressure bleeder begin forcing DOT 5 through the system until all the DOT3 has been expelled and DOT5 starts coming out.
