Problem: Regular DOT type 3 or 4 brake fluid attracts moisture from the atmosphere, degrading the fluid and causing corrosion in brake and clutch cylinders. Girling clutch cylinders are aluminum and are especially prone to this problem. Silicon fluid does not attract moisture and holds up to the high brake temperatures involved in racing, but it has three drawbacks: it is expensive, requires a complete drainage and cleaning of your hydraulic system before installation, and it rapidly rots out the brake light switch on those cars equipped with the fluid-activated model. I can personally attest to this (at great length).

Solution: Castrol LMA (stands for "Low Moisture Activity") fluid does not corrode cylinders or brake light switches, requires only a flushing of the type 3 or 4 fluid from your system, and is inexpensive. I don't know how suitable it is in a racing application, but I recommend it highly for street use.