Reply to "Brake fluid?"

I'll expand a little on what Scott said. The hill climbers were some of the first to use Silicone fluid due to the boiling point being higher then conventional fluid. They soon had brake failure but could not figure out why.

Turns out since it is not absorbed ANY fluid in the system will settle into the lowest point generally being the calipers. A drop or two of water in a silicone system is enough to boil water and to lose your brakes.

Conversely, traditional fluid can absorb a tea-spoon of water and basically spread it through the system and still not fail your brakes because you would still have a minute amount of water in your calipers.

Keep in mind we are suppose to change or flush our brake fluid every 2 years....but who does. I know I don't. In a street driven car it's 1 year generally for a silicon system and I would avoid the mountains at that.

When racing it I have always heard that if you use silicone fluid you are suppose to change it before EVERY SINGLE RACE.

Why do people like it? Because most people are not very good at bleeding brake systems without making a mess threatening the paint. I am in that boat too. I keep a bottle of Windex and a rag and immediately clean up any drop which does not get into the system.

But I also think the "silicone is great" movement is almost religious in nature. In fact I have seen issues in people cars with pure silicone oil while the mix seems to be ok.

The great benefit of silicone is it's industrial level of sliperyness. It has also been found that the silicon oil has some draw backs. One is it does not breakdown contaminants in the oil like natural oils. It is also so slippery that if you loose oil pressure say in a turn there is not enough adhesion and you fry your bearings a lot faster.

A lot of the problems can be fixed with additives but the more additives, the less oil. The best additive is traditional oil!

Back in the 80's Shell Oil came out with a full silicon oil for airplanes. Engines and controllable pitch propellers were not making it to overhaul. Turns out they were loading up with sludge and it would not break it down. They payed out millions in lawsuits and as far as a couple years ago there still were no full silicon oils for piston powered airplanes.

Turbines are different as there is no blow by in the oil system like in a piston powered engine. The silicone fluid has worked wonderful for turbines.