"Lifespan" or "Shelf life" of brake fluid?

Hello everyone!

I have always taken my Golf III Variant to the same VAG dealership for its regular inspections.
I recently went to ATU last Saturday to have my brake pads replaced. There, it was discovered that my brake fluid was no longer in good condition. O. be.
Note on the invoice: (... contains more than 3% water). The test was performed by the mechanic in my presence using a testing device, similar to a pen. After unscrewing the container, he immediately said that the liquid looked very dark.
However, according to VAG records, she was only registered approximately 1 year ago. Inspection changed.
Could it be that she aged faster, or was I perhaps only charged for the exchange without the actual exchange being carried out?

What do you think? Can liquids age faster? Should I have the fluid replaced, even though it's not yet 2 years old?
At VAG, it's always just based on time (2 years) and not on condition.

Best regards, D.

Hi D.
I work in a company that manufactures brake service equipment, and as the saying goes: the shoemaker has the worst shoes. My colleague, who drove his Mitsubishi for 7 years, never changed the brake fluid (BF), even though he works at the 'source' like I do. Generally, brake fluid is changed every two years. Measuring the water content in the reservoir is, in my opinion, more of a sales argument than a necessity, because: the ventilation in the cap inevitably introduces air with its water content to the brake fluid, and due to the high affinity for water, the boiling point of the brake fluid in the reservoir decreases. If the mechanic were to take the brake fluid sample directly from the bleed nipple of the wheel cylinder, the test result would look completely different. Furthermore, 'with such a device,' the electrical conductivity of the brake fluid is practically measured and converted into a percentage of water, which, in my opinion, is very inaccurate. There are brake fluids that have a practically infinite electrical resistance (e.g., I believe Ate Blue Racing is one). In reality, what matters is the (wet) boiling point of the brake fluid, and this is measured accurately with slightly more expensive equipment (e.g., SP = 130 degrees Celsius, should be 160-180 degrees Celsius). At the company, we have a similar device from Ate, and I've done some experiments. I can only say: you really need to put a significant amount of water in there for the SP (Specific Gravity) to drop by 10-20 degrees (in a test with about 20ml, it took about 10 drops of water)!!!
If the brake fluid is already being analyzed for water content/boiling point, a sample should be taken from the bleeder nipple on the driver's side - but no one bothers to do that.
My recommendation: replace it no later than every 2 years or after 20,000 km, or before a trip through a mountain pass, because it's only after a long downhill stretch that a lowered boiling point can become dangerous!
Best regards,
Alchard.

Well, I guess I've found an expert right away.
I also visited your website, www.Stierius.de.

You're welcome, Alchard.

Devices that look like pens don't work. Only devices that measure the boiling point of the brake fluid in real-time are acceptable. So, there's a need for... B. Properties: Boiling point approximately 190°C.
Go to a workshop that has such a device (e.g., an Ate BremsenCenter, but also others) and have the actual boiling point measured. That's probably even a free service.
Once it reaches a boiling point of 160°C or lower, quickly change it. For comparison: the new liquid has a temperature of approximately 260°C (depending on the type).
Greetings Lanz

Apart from the test, I don't think brake fluid is unusable after just one year. The lifespan certainly varies depending on driving style, but I don't think it degrades that quickly. VW probably sets the two-year limit for safety reasons (so that authorized workshops can also make some money).
But let's talk about ATU:
I heard that sometimes, when you have a service done by them, the original service booklet from the manufacturer disappears.
'DID I REALLY JUST HEAR THAT? I'M NOT SURE IF IT'S TRUE.'
Has this ever happened to anyone else?

But let's talk about ATU:
I heard that sometimes, when you have a service done by them, the original service booklet from the manufacturer disappears.
'DID I REALLY JUST HEAR THAT? I'M NOT SURE IF IT'S TRUE.'
Has this ever happened to anyone else?

Nope, I avoid chains like the devil avoids holy water.

But if even a single Aldi receipt were missing from my car after the visit to the workshop, I would grab the chainsaw and go there to express my displeasure...

CU Gremlin.