Currently reading: How defective brake fluid could put UK motorists at risk
More than a quarter of cars in the UK could be using ineffective brake fluid, increasing the likelihood of an accident

Research has suggested that more than a quarter of all the cars in the UK have defective brake fluid.

Now you, like us, might raise an eyebrow at that statement. The research, carried out for Cosan Lubricants’ Mobil Car Care range, however, bears some consideration.

Brake fluid is hygroscopic, meaning that it absorbs water from the atmosphere. Over time this reduces its effectiveness by lowering its boiling point.

When the fluid boils, vapour is produced – which is compressible – resulting in a soft brake pedal and a decreased, or non-existent, braking effort.

Cosan says that brake fluid, which has a typical boiling point of between 230-260 degrees C when new, becomes all but useless once it boils below 180deg.

Brake fluid expert Alba Diagnostic concurs, suggesting that brake fluid should be changed when its boiling point is down to 200deg C — and it’s below this figure that the research suggests more than a quarter of all cars will boil their fluid.

After all, how many of us are particularly attentive as to what goes into our brake fluid reservoirs? We may intermittently check the levels, but few of us are likely to go any further.

Many of us use whatever brake fluid tends to be handy — which might be a contaminated bottle that’s been on the shelf for a while. That’s assuming, of course, that the fluid has even been changed in recent history.

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.

"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."

So if you’ve only been intermittently checking your brake fluid’s levels, or don’t know when it was last refreshed, perhaps it’s time to consider a change. After all, for £100 including labour, it’s cheap insurance.

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Add a comment…
CWBROWN 20 August 2014

Mismatched tyres would probably be a larger issue

The issue with water contaminated brake fluid is it rusts out the ABS pump. Few in the UK will overheat their brakes unless they are an utter headcase, or driving a 44 ton truck.

The number of cars I see with mismatched part worns on (With 2mm on one side and 7 mm on the other on an axle!)= a real danger when it rains or snows.

Frightmare Bob 20 August 2014

I note that the "research"

I note that the "research" has been carried out by a company with a vested interest in selling us more brake fluid.
scotty5 20 August 2014

A money making racket.

Of all the cars I've owned over the past 30 years, only TWO have had a brake fluid change, neither of them requested by me. The Merc had it changed as it was part of a fixed price service (the cheapest quote for it's 2nd service was an eye watering £580 - a fluid change for the brakes and a change of underpants for me £580 for a 1.8 C-Class!). The other change was part of replacing a faulty ABS sensor on my Golf. As I drove out the garage I felt the brakes a little spongy but thought nothing much of it. Several miles later and my brakes failed - luckily there were no other vehicles around at the time. The garage hadn't bleed the brakes properly which I guess is another downside of car maintenance - "if it ain't broke..." Not saying I'd never have a brake fluid change, but every 2 years is simply ridiculous. If it was dangerous, then it would be part of MOT and manufacturers would insist on it rather than recommend it. By the way, in all those 30 years of owning a car I have NEVER heard of anyone having an accident because their brake fluid wasn't up to the job.