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Brake Fluids

silicone brake fluid?

Moparts Member
Posts: 3788
From: Peoples Republic of New Jersey
Registered: May 2001
posted 11-03-2002 03:19 PM

something i never thought of (member mentioned it) was the silicone fluid not making your paint disappear. the instructions that were in the dart i brought (master power brake) state that if silicone fluid is used it voids the warranty. are there any known incompatibilities between this fluid and sealing components?


Posts: 2844
From: Detroit, MI
Registered: Feb 2000
posted 11-03-2002 03:30 PM

No problem in my GTS's system. Have had it in there for 3 years now. It's really nice to bleed the brakes now. When you're done, just spray the axle housing/backing plates with Windex, and wipe. Just be sure to let the fluid sit in the master for a hour or two before bleeding. It does have micro bubbles of air that need some time to rise to the surface in the master.



Moparts Member
Posts: 584
From: Edmonton AB Canada
Registered: May 2000
posted 11-03-2002 03:40 PM

I know someone who made mistake of mixing the two fluids and wound up with a big fix-em-up job.
So, if you are going to use, consider purging your whole system of the dot3 before going to dot5.


Moparts Member
Posts: 404
From: indiana,u.s.
Registered: Feb 2002
posted 11-03-2002 03:52 PM

i'm assuming you're talking dot5 fluid. i use it in my r/t and will use it in my 65 coronet. no problems at all. if you're doing a new front to back system i'd highly recommend dot 5. dot5 and dot 3 will not mix, so flush anything that has had dot 3 in it.


Moparts Member
Posts: 904
From: El Cerrito (by San Francisco), CA
Registered: Aug 2000
posted 11-03-2002 04:39 PM

I don't know where people get the notion that DOTs don't mix (I had it too) but e'burger says that they must in order to be saleable and I tend to agree (even though when I put it in my car I flushed out the lines with denatured alcohol and rebuilt everything except the p. valve). I have both and I am going to mix them in a glass and see what happens -- I will report back. Kim


Moparts Member
Posts: 5308
From: 742 Evergreen Terrace, Souderton, PA
Registered: Nov 1999
posted 11-03-2002 04:48 PM

I've been running 5 for just over a year now I guess. No problems, and stiffer brakes too. Best part is if it ever leaks, it won't hurt anything.
Don't know why it would void your warranty, unless it swells rubber or something.


Moparts Member
Posts: 584
From: Edmonton AB Canada
Registered: May 2000
posted 11-03-2002 05:45 PM

http://www.tccoa.com/brake-fluid/ might be a good read.
and another.


Moparts Member
Posts: 1494
From: lyons.il.USA
Registered: Oct 2001
posted 11-03-2002 07:05 PM

We have a couple models of Hyster lift truck that require DOT5, the rest take DOT3. The factory released a service gram a couple years ago about mixing the two fluids. Basically, it stated that even though it turns into a really nasty looking mess, it will still work. It actually looks kinda like DOT# that has drawn water


Moparts Member
Posts: 1512
From: New Ulm, MN USA
Registered: Nov 1999
posted 11-03-2002 07:44 PM

To get the benefits of Dot 5 it's important to get as much of the old Dot 3 out of the system as possible.
I would shy away from using alcohol to clean the system, as it would be extremely difficult to get all of it out before you put in the Dot 5 (I would rather have a tablespoon of reminant Dot 3 in the system than a tablespoon of alcohol!).

Dot 3 and Dot 5 will definately mix (it's called "miscability" and they have to be able to combine and be compatable in order to be DOT certified. An analogy would be the difference between 87 octane and 93 octane gasoline; You can mix them obviously.


Moparts Member
Posts: 2483
From: Circleville, Ohio, US
Registered: Jan 2000
posted 11-03-2002 08:55 PM

I've used in my last 2 cars with no issues!!! It'll stop a 3350 131MPH street car.


Moparts Member
Posts: 176
From: marietta,ga. usa
Registered: Jan 2002
posted 11-04-2002 08:02 AM

In some systems the DOT 5 is not compatible with the rubber and dissolves them to a gooey mess. We no longer use it at my shop for this reason.


Moparts Member
Posts: 1380
From: Old town,fl,usa
Registered: Oct 2001
posted 11-04-2002 09:16 AM

if you were flushing the systems with alcohol,that is where the gooey mess would originate.


Moparts Member
Posts: 307
From: Portsmouth, Va. 23703
Registered: Apr 2001
posted 11-04-2002 09:44 AM

I've done brake jobs off and on for 30 years, and alcohol is the prefeered solvent for cleaning brake systems. Flushing the system with alcohol is the best way to insure there is no residue of dot3 left in the system. Alcohol will evarporate as the brake system is not hermetically sealed.
That having been said, from Department of Transportation stand point DOT 3 & DOT 5 are compatabile and mixable (miscability) sp. But my personal preferance is to flush the system completly then add the Silicone based fluid.


Deric Hebert
Moparts Member
Posts: 403
From: Amarillo, Texas USA
Registered: Jun 2002
posted 11-04-2002 10:13 AM

My understanding of DOT 5 is that although it has a higher boiling point, it has no inherent lubericating properties. I would not mix them. DOT 3 mixed with DOT 5 is not DOT 4 !!! Use one or the other. I will stay will DOT 3 and keep it off my paint!


Moparts Member
Posts: 2181
From: Port Huron, MI area
Registered: Nov 1999
posted 11-04-2002 10:33 AM

I've had DOT5 in my Road Runner since 1995 with no problems yet.



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