Truck, Tractor & Earthmoving - Brake Fluids

Truck brake fluid for hydraulic brakes and clutches

Greyhound Lubricants truck brake fluid is a DOT 4 glycol fluid for the hydraulic brake and clutch circuits on light and medium trucks, buses, tractors, trailers and earthmoving equipment, including vehicles fitted with ABS and electronic braking. Many heavy trucks run full air brakes and need no brake fluid, but the hydraulic clutch on most of them does, and the lighter trucks, bakkies and buses in a mixed fleet run hydraulic or air over hydraulic brakes where the fluid condition decides how the pedal feels on a long descent. The high dry and wet boiling points of DOT 4 keep the pedal firm under repeated hard braking.

Managing truck brake fluid across a fleet

Brake fluid absorbs moisture through the hoses and reservoir cap, and a loaded truck on a long downhill is where a two year old fluid boils and the pedal goes to the floor. Change every two years as a fleet rule regardless of mileage, test the water content with a tester at each service and record it, and bleed from the wheel furthest from the master cylinder. Hydraulic clutches on air braked trucks are usually forgotten and run on the original fluid for years; put them on the same schedule. Use only sealed containers, because an opened drum of truck brake fluid absorbs moisture on the shelf, and never mix glycol DOT 4 with silicone DOT 5. Brake fluid strips paint, so rinse spills on the cab immediately. Greyhound supplies 500 ml and 1 litre for top ups and 5 litre for the workshop.