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Synthetic DOT4 Brake Fluid

1K views 2 replies 2 participants last post by  Alfaspider1987 
#1 ·
Good day all. I have run this past a AR FB site but would welcome views from fellow Alfa owners on here on a potential problem I have made for my self.

I have recently replaced the whole of my braking system, only the callipers remain original but have been fully refurbed and rebuilt.

I refilled the system with DOT4 (synthetic) brake fluid but having completed the bleeding process I read a FB thread that said not to use synthetic fluid[emoji53]

Do I need the change this fluid out for none Synthetic fluid or will it be ok to use as it’s a new system?

The car is a Spider S3 and
I filled the system 2 weeks ago, I’ve attached a picture of the fluid used for reference. Hoping for good news[emoji3].


Tire Automotive tire Product Water Automotive wheel system



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#2 ·
The "Synthetic" label is mostly marketing hype. DOT 4 is the right stuff to use. All brake fluid is synthetic in that it is not found in nature but made in a laboratory/factory. The advice to avoid synthetic brake fluid is probably referring to DOT 5 which is silicone based. The two types should not be mixed.

Bottom line - DOT 3 & DOT 4 are glycol based and are compatible with each other. DOT 4 has a higher boiling point. If you mix them you get the lower boiling point of the DOT 3. DOT 3 & DOT 4 are hygroscopic - they will absorb moisture. For this reason you should always use fresh brake fluid and flush the system every few years. DOT 5 does not absorb moisture. But if any moisture does get into the system it will pool and can cause corrosion. To confuse the issue even further there is a DOT 5.1 (not commonly found in auto parts stores). DOT 5.1 is also glycol based and has an even higher boiling point than DOT 4.
 
#3 ·
This sounds very reassuring and makes perfect sense. As usual thank you for your time explaining this in detail. I’m sure I’ll be back with more problems soon. Getting ready to start the car in the next few weeks after 12 years.....fingers crossed.


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