The difference between synthetic brake fluid and normal (polyglycol) brake fluid is that polyglycol absorbs water and moisture from the air over time, that is why you need to change it perodically. When polyglycol absorbs water, the water obviously has a much lower boiling point than the brake fluid and therefore boils before the fluid, creating vapour bubbles. This can lead to a total loss of the vehicle's braking. On the other hand, synthetic fluid repels water and never needs changing. This also helps keep rust and corrosion out of you braking system. It normally has a higher boiling point than polyglycol so you shouldn't ever get your brake fluid boiling even on a track day
Hope this helps:smilegrin: