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Brake and Clutch Fluid

twiget

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I was cleaning under the hood today, and I checked the brake and clutch fluid reservoirs. The clutch fluid is almost black, and should probably be changed. I'm not too surprised about that, because I did do 5 runs down the strip a few weeks ago.

The brake fluid surprised me though, it is dark brown and smells burnt. She's only got 5400 miles on her, and other than the runs down the strip, and a couple 100+mph runs, I haven't driven her that hard. Is it normal for brake fluid to turn dark so quickly?

Jason
 
I agree with c4c5, brake fluid in C4/5/6 rapidly discolors. My own theory is that part of the discoloring related to the aluminum parts in the brake system.

What wasn't said is that brake part durability can be greatly extended if the system gets a regular flushing, ie: periodic fluid changes....not just bleeding but flushing.

I suggest every 3yrs or 36,000 miles for this.

Do that and brake parts, especially the expensive-to-replace, brake pressure modulator valve, may last longer.
 
Clutch/brake fluid turns dark because of oxidation or heat related issues. When it's dark, it has degraded. I have changed the reservior for the clutch quite often in my C6Z. To the previous poster, aluminum oxide is chalky white in color. I'm of the belief that do to the close proximity of the headers/exhaust system, the clutch line gets "super heated" and causes the accelerated degradation. I bet that if there were some effective insulation on the line by the heat source (exhaust), we'd only have to worry about heat generation @ the clutch mechanism itself.

What say you?
 
HI there,
The black discoloration is from carbon black from the sealing diaphragm leeching, creating the discoloration.
GM has done extensive testing on this to determine the cause.
This was a big thing with c5.
Fact is, there is no correlation between coloring and lubricity/contamination of the fluid.
TESTING, is the only way to accurately determine fluid quality.
Allthebest, c4c5
 
HI there,
The black discoloration is from carbon black from the sealing diaphragm leeching, creating the discoloration.
GM has done extensive testing on this to determine the cause.
This was a big thing with c5.
Fact is, there is no correlation between coloring and lubricity/contamination of the fluid.
TESTING, is the only way to accurately determine fluid quality.
Allthebest, c4c5
You are correct about testing being the only way to evaluate a fluid's quality.
The sealing diaphragm may be a "contributing factor" but rest assured, heat/oxidation causes DOT4 to darken also. Now, which one causes the largest effect would require control testing in a lab. Either way, I avoid clutch "pedal stuck" problems by changing the fluid in the res often. I am alarmed how quickly it changes color however. I don't drag race my car as it isn't a dragster. I don't do "holeshots" with it either, just drive it quite easily. My brake fluid looks new...after 18,000 miles. (I still have the OEM tires on it!)

Allthebestbackatcha!:thumb
 
I change my clutch fluid often, its easy.
Suck out the old, fill it up with the new. Close the lid and pump the clutch about 20 times. Repeat a few times and the fliud will be new and clean.
 
HI there,
The black discoloration is from carbon black from the sealing diaphragm leeching, creating the discoloration.
GM has done extensive testing on this to determine the cause.
This was a big thing with c5.
Fact is, there is no correlation between coloring and lubricity/contamination of the fluid.
TESTING, is the only way to accurately determine fluid quality.
Allthebest, c4c5

My belief, expressed above, about the black stuff in the fluid, was misguided. I was not aware of that GM testing which determined the cause as carbon black.
 

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