Guidelines And Background: Background
The oil must be replaced because it is hygroscopic (the fluid absorbs water molecules from the air). This absorption of water occurs through the brake hoses and brake fluid reservoir. These components are rubber and plastic respectively and are not completely sealed against water molecules. An increased water content in the brake fluid dramatically reduces its boiling point and causes corrosion in the brake system components. This results in damage to the brake system. Braking performance deteriorates markedly.
NOTE:
Use only Volvo Genuine Parts brake fluid designated DOT 4+. Never reuse brake fluid. Always keep the brake fluid sealed in the original packaging.
NOTE:
Continually check that there is sufficient brake fluid in the brake fluid reservoir when changing brake fluid.