DOT4 and DOT5 brake fluids
The use of silicone brake fluids in classic car brake and clutch systems is a topic of interest to enthusiasts as we have seen from the the brake fluids thread on the V8BB. So here we are gathering together useful references with facts and comments on the key issues and concerns. The references will be expanded as more material is identified. More
Note: these references are mentioned simply for information and neither the V8 Register nor its officers and committee members recommends the use of slicone based fluids. If in doubt consult an MG specialist listed in the V8LIFELINE.
DOT4 and DOT5 brake fluids
If silicone is introduced into an older brake system, the silicone will latch unto the sludge generated by gradual component deterioration and create a gelatin like goop which will attract more crud and eventually plug up metering orifices or cause pistons to stick. If you have already changed to DOT5, don't compound your initial mistake and change back. Silicone is very tenacious stuff and you will never get it all out of your system. Just change the fluid regularly. The British Cycle Supply Company does not recommend use of DOT5 silicone brake fluid on British motorcycles equipped with any AP Lockeed disc brake components. (10.1.05) More
DOT3 v DOT5 brake fluid
Wrenchbender is MIke Dixon, veteran of the motorcycle industry, who after receiving initial training through Los Angeles Trade Technical College's Motorcycle Repair Program (a two-year program among whose instructors were Joe Minton and Pat Owens), was one of the first 500 of Honda's Registered Technicians, attended most of the Big Four's factory training courses, and plied his trade as a metro L.A. area Honda mechanic and service manager, suspension tuning shop owner and performance engine builder. His comparative analysis is a good read. More
Braking point - a query on brake fluid
Honest John's Agony Column in the Daily Telegraph - Motoring section on Saturday 29th May 1999 responded to a query from a reader on silicone brake fluid. More

Silicone brake and clutch fluid DOT5 - for reference a brief note from Automec, the automotive brake pipe and parts specialist . More
So you think silicone fluid is the answer to your braking problems? Not according to a US correspondent, it isn’t!
Bruce Anderson says "I’m not against silicone fluid, but I feel it’s not acceptable for cars that are actually driven – and especially those, such as Porsches, that tend to be driven hard. In fact, one driver, Bobby Rahal, told us that it scared him to death, and that if we didn’t take the stuff out of the system we would have to drive the car ourselves." (March 1999 - 911 & Porsche World)
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This article is featured on the Automec website. Bruce Anderson says " as you might expect of someone who sells the stuff, Ray Smith suggests that silicone-based fluid could be the solution to all our braking problems – which I certainly don’t feel is the case. He also claims that changing from an older, polyglycol fluid to silicone fluid is straightforward. Once again, I would suggest, it is not."
Fluid movement
Ray Smith isn't just passionate about brake fluid, he's positively obsessed with the stuff. In fact, he could easily list it as his specialist subject in Mastermind. Talk to him for even a few minutes, though, and you begin to realise that there's rather more to this seemingly arcane field of automotive engineering than meets the eye. Spend an hour with him and you'll soon be zealously spreading the word yourself. Interview by a converted Philip Raby. (October 1998 - 911 & Porsche World) More
This article is featured on the Automec website. Ray Smith, from the Buckingham-based Automec Equipment and Parts Limited, says "‘Since we first launched our silicone brake fluid here in the UK in 1982, we have been steadily convincing
people that there is a genuinely viable alternative to conventional brake fluid; a fluid that you really can fit and then forget for the life of the car.’
V8 Register - MG Car Club - the leading group for MG V8 enthusiasts at www.v8register.net