Dot 5
Le Mans Master
Joined: Dec 2004
Posts: 5,759
Likes: 539
From: AZ
St. Jude Donor '06-'08-'10-'11-'12-'13 '14-'15-'16-'17-'18-'19
My guess, and it's purely a guess, is that no, DOT5 shouldn't be used. I only say that because brake systems using DOT3/4 should not use DOT5 due to incompatible materials and other issues. I assume the clutch system might have the same concerns so I personally wouldn't use it.
CF Senior Member
Joined: Feb 2006
Posts: 23,313
Likes: 25
From: Tucson Arizona
I believe DOT 5 is silicone based and should not to be used in the C6....it may damage the seals. I use Prestone Dot 4 clutch fluid and Motul 600 brake fluid. You can also buy GM DOT 4 brake/clutch fluid in the small metal cans.
Last edited by Wayne O; Apr 26, 2008 at 08:04 PM.
Instructor
Joined: Apr 2006
Posts: 120
Likes: 1
From: Fairfax VA
I was just reading about this. Good thing you got it out. DOT5 is silicone based and is not compatible with DOT 4 or other a polyethylene glycol-based hydraulic fluids. There is a DOT 5.1 fluid that has a higher boiling point than DOT 4. There was another thread posted here last week with this link that talks about DOT 5.1 fluids. http://en.wikipedia.org/wiki/DOT_5.1.
I just bought some put haven't put it in yet...apparently it is more commonly used in motorcycle brakes.
I just bought some put haven't put it in yet...apparently it is more commonly used in motorcycle brakes.
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Brett Foote
Team Owner
Joined: Mar 2008
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From: Southern Utah
Drifting
Joined: Feb 2007
Posts: 1,537
Likes: 1
From: Southlake Texas
Make sure you flushed all of it out.
"If silicone is introduced into an older brake system, the silicone will latch unto the sludge generated by gradual component deterioration and create a gelatin like goop which will attract more crud and eventually plug up metering orifices or cause pistons to stick. If you have already changed to DOT 5, don't compound your initial mistake and change back. Silicone is very tenacious stuff and you will never get it all out of your system. Just change the fluid regularly. For those who race using silicone fluid, I recommend that you crack the bleed screws before each racing session to insure that there is no water in the calipers."
ONLY flush with Dot 3-4 brake fluid.
Pro
Joined: Jan 2006
Posts: 703
Likes: 1
From: Berwyn IL
I would be inclined to try DOT5, but ONLY if I had the clutch system apart and could thoroughly clean it of the glycol fluid. I have had good experience with it in the 1970 Corvette, but I installed it when I overhauled the brake system over twenty years ago. There has been no leaks, and no compatibility issues, and no sign of sludge either. Best of all there is no paint damage from brake fluid.
Drifting
Joined: Oct 2004
Posts: 1,612
Likes: 0
From: Streamwood IL
DOT 5 is NOT compatable, and if used in the brakes, could destroy the ABS module.
DOT4 is overkill for the clutch. DOT3 is reccomended.
DOT4 fluid, while having a higher boiling point, is best when it is "dry." DOT3/4 fluid will absorb moisture from the air, and it will eventually spoil the fluid. DOT4 will absorb water much faster than DOT3.
If you run DOT4 fluid, you should flush it annually. DOT3 should be flushed ever 3 years or so. (In either the brakes OR the clutch.)
If you run your car on a track (road course) then go to DOT4 in the brakes. If not, no matter HOW hard you drive on the street, I reccomend DOT3.
I ALWAYS reccomend DOT3 for the clutch.
DOT4 is overkill for the clutch. DOT3 is reccomended.
DOT4 fluid, while having a higher boiling point, is best when it is "dry." DOT3/4 fluid will absorb moisture from the air, and it will eventually spoil the fluid. DOT4 will absorb water much faster than DOT3.
If you run DOT4 fluid, you should flush it annually. DOT3 should be flushed ever 3 years or so. (In either the brakes OR the clutch.)
If you run your car on a track (road course) then go to DOT4 in the brakes. If not, no matter HOW hard you drive on the street, I reccomend DOT3.
I ALWAYS reccomend DOT3 for the clutch.
Pro
Joined: Jan 2006
Posts: 703
Likes: 1
From: Berwyn IL
DOT 5 is NOT compatable, and if used in the brakes, could destroy the ABS module.
DOT4 is overkill for the clutch. DOT3 is reccomended.
DOT4 fluid, while having a higher boiling point, is best when it is "dry." DOT3/4 fluid will absorb moisture from the air, and it will eventually spoil the fluid. DOT4 will absorb water much faster than DOT3.
If you run DOT4 fluid, you should flush it annually. DOT3 should be flushed ever 3 years or so. (In either the brakes OR the clutch.)
If you run your car on a track (road course) then go to DOT4 in the brakes. If not, no matter HOW hard you drive on the street, I reccomend DOT3.
I ALWAYS reccomend DOT3 for the clutch.
DOT4 is overkill for the clutch. DOT3 is reccomended.
DOT4 fluid, while having a higher boiling point, is best when it is "dry." DOT3/4 fluid will absorb moisture from the air, and it will eventually spoil the fluid. DOT4 will absorb water much faster than DOT3.
If you run DOT4 fluid, you should flush it annually. DOT3 should be flushed ever 3 years or so. (In either the brakes OR the clutch.)
If you run your car on a track (road course) then go to DOT4 in the brakes. If not, no matter HOW hard you drive on the street, I reccomend DOT3.
I ALWAYS reccomend DOT3 for the clutch.
Please post the evidence for DOT-4 absorbing moisture more rapidly than DOT-3. I want to learn more about that.
DOT-5 is not recommended for ABS equipped brake systems because of the propensity of air entrainment in the ABS system -- However, as far as I can determine no one has published any experiments to verify these concerns. If anyone knows of any such experiments, please let us know.
Drifting
Joined: Oct 2004
Posts: 1,612
Likes: 0
From: Streamwood IL
http://www.advanceautoparts.com/engl...20011001bb.asp
http://www.stoptech.com/tech_info/wp...fluid_1a.shtml
I was oversimplifying by saying it absorbed water more quickly. What I meant was that water absorbtion causes a performance drop-off more quickly with DOT4 than DOT3.
I just went and doublechecked the owner's manual, and sure enough they do call for DOT4 fluid in the clutch. That seems odd to me, and I admit I don't understand why they call for that. However, since they do call for DOT4 fluid, I will change my reccomendation to align with the GM engineers.
DOT3 for the brakes,
DOT4 for the clutch.
Most brake fluid is hydroscopic: It absorbs water. On the positive side, any moisture that enters the system—through condensation, through rubber parts such as seals and hoses or through an unsealed bottle of brake fluid—is dispersed throughout the fluid. That way, chances of localized corrosion and fluid freezing are minimized. On the other hand, absorbed moisture lowers the fluid's boiling point, raises its freezing point and degrades its anti-corrosion additives.
DOT 4 fluids are also glycol ether based, but have a measure of borate esters thrown in for improved properties including increased dry and wet boiling points. A seldom talked about characteristic though is that because of this chemistry, the DOT 4 fluid will have a more stable and higher boiling point during the early portion of its life, but ironically once the fluid does actually begin to absorb water its boiling point will typically fall off more rapidly than a typical DOT 3.
I just went and doublechecked the owner's manual, and sure enough they do call for DOT4 fluid in the clutch. That seems odd to me, and I admit I don't understand why they call for that. However, since they do call for DOT4 fluid, I will change my reccomendation to align with the GM engineers.
DOT3 for the brakes,
DOT4 for the clutch.
Navigator
Joined: Apr 2005
Posts: 9
Likes: 0
Help!!!
I am currently trying an experiment with DOT 5 in my C5 brake system. This was a huge blunder/laps of judgement on my part, but now it seems like I am stuck with it. I am looking into what it would take to reverse my mistake besides thousands of dollars.
Any suggestions on how to switch back to DOT 3/4 would be appreciated. One I have heard was flushing with Denatured alcohol to remove the silicone from the lines. This will either work or cause worse problems, so needless to say I have not tried yet.
Any suggestions on how to switch back to DOT 3/4 would be appreciated. One I have heard was flushing with Denatured alcohol to remove the silicone from the lines. This will either work or cause worse problems, so needless to say I have not tried yet.
CF Senior Member
Joined: Feb 2006
Posts: 23,313
Likes: 25
From: Tucson Arizona
I am currently trying an experiment with DOT 5 in my C5 brake system. This was a huge blunder/laps of judgement on my part, but now it seems like I am stuck with it. I am looking into what it would take to reverse my mistake besides thousands of dollars. Any suggestions on how to switch back to DOT 3/4 would be appreciated. One I have heard was flushing with Denatured alcohol to remove the silicone from the lines. This will either work or cause worse problems, so needless to say I have not tried yet.
Any suggestions on how to switch back to DOT 3/4 would be appreciated. One I have heard was flushing with Denatured alcohol to remove the silicone from the lines. This will either work or cause worse problems, so needless to say I have not tried yet.
Pro
Joined: Jan 2006
Posts: 703
Likes: 1
From: Berwyn IL
Alcohol is a solvent for glycol based brake fluids (DOT-3, 4 & 5.1), but I doubt it works for DOT-5. You might experiment a little to see what alcohol mixed with DOT-5 does. See if they mix together in a small container.
If alcohol does not mix with the DOT-5, you might try contacting the brake fluid manufacturer to see what they recommend as a solvent.
As Wayne has suggested, you will need a Tech-II, or the like, to actuate the ABS system to get all the DOT-5 out.
If alcohol does not mix with the DOT-5, you might try contacting the brake fluid manufacturer to see what they recommend as a solvent.
As Wayne has suggested, you will need a Tech-II, or the like, to actuate the ABS system to get all the DOT-5 out.
Last edited by 9C1; May 5, 2008 at 10:37 AM. Reason: spelling