Inspection Check
Brake fluid
Hygroscopic hydraulic fluid (typically DOT 4 in modern cars). Should be changed every two years regardless of mileage.
Brake fluid absorbs moisture from the atmosphere through seals and reservoir vents. Water lowers the boiling point and can cause the fluid to vaporise under hard braking, leading to a long or sinking pedal.
A falling reservoir level between services usually indicates worn brake pads rather than a leak — as the pads wear, the calliper pistons extend and the fluid level drops accordingly.