Sorry, I guess I wasn't paying attention and didn't realize it was time for
the annual British Car Argue About Brake Fluid Festival. -- what must it be
now, the 40th annual re-enactment of this ancient brawl?
Fact 1: Neither glycol and silicone fluids, used separately, will not harm
modern synthetic rubber seals.
Fact 2: Glycol is hygroscopic and therefore must be flushed and replaced
every two years.
Fact 3: Silicone fluid won't harm paint; Glycol will.
Fact 4: Glycol gives superior response because it doesn't compress as much
before pushing through the system.
Fact 5: Never, ever mix glycol and silicone fluids in any amounts, because
they cancel out one another's additives and will cause the seals in the
system to fail.
Conclusions: Use glycol in cars that are driven frequently, but be very
careful when you refill the system so you don't spill it on your paint, and
change it regularly. Use silicone in show cars that are driven less hard and
And those were the same conclusions that I arrived at after research 14
years ago when i wrote my first article on brake fluids for British Car
Magazine, and no one has yet contradicted any of those facts, except for the
chorus that is a traditional part of this festival, where they array
themselves and sing antiphonally across the grease pit: "Silicone fluid is bad"
and from the other side, "Glycol Fluid is bad."
Suggested annual donation $12.75