When was the last time you changed your brake fluid? Perhaps you're not aware that the liquid which keeps you from hitting the car in front every time you step on the brake pedal requires changing? If so, you're not alone, as new research suggests that around a quarter of British motorists are driving around with ageing brake fluid in their cars.
A study carried out by Brazilian lubricants firm Cosan, which revealed that 26.5 per cent of vehicles inspected by independent garages were using sub-standard fluid. While the majority of drivers are aware of the need to keep engine oil and a variety of other fluids topped up and fresh, brake fluid often gets overlooked, which can cause problems if it is particularly old.
The problem occurs as brake fluid is hygroscopic, meaning it absorbs moisture from the air. This has the effect of lowering its boiling point over time, resulting in less effective stopping performance during periods of extreme of prolonged braking.
While fresh brake fluid typically has a boiling point of 230-260 degrees centigrade, it should be changed when this drops to around 200 degrees. After the boiling point drops to 180 degrees due to increased levels of water, it becomes all but useless in anything less than moderate braking, and could result in the brake pedal going to the floor or the car with no stopping power being transferred to the brake calipers.
Mike Bewsey, of Cosan Lubricants, said: "Many drivers mistakenly believe that if their car has passed its MOT, all of the lubricants and chemicals within it are up to scratch," Autocar reports.
"The only way to check the quality of brake fluid is to test its boiling point temperature. As that is not part of the MOT, the onus is clearly on motorists to ensure that their car is safe."
If you're concerned that the brake fluid in your car may be past its best, it costs around £100 including labour to have it changed. It's a job that could be done at home, provided you're mechanically competent.