DOT 5 - Is this new to anyone else?

[Donald H.]

I used DOT 5 brake fluid when I restored my 66 (non-power), i.e. new lines, rebuilt calipers and rebuilt master. I only have 300 or some miles on the car, but I've been happy with the brakes and had no trouble bleeding the system.

I'm in the process of installing new brake lines on my 67. I also have the calipers off and apart for cleaning and new seals. I will also be taking master cylinder apart for cleaning. This car had Dot 3 fluid in it when I got it. I had an accidental fluid spill at the master cylinder and of course lost paint on the master cylinder, bracket and firewall. Not major just irritating, so I was planning to switch to DOT 5 with all the working I'm doing on the car.

Now here is the rub. I was ordering some parts from Corvette Stainless Steel Brakes and saw a warning on the upper left of their web pages Dot 5 Brake Fluid Will Void Warranty. If you click on this warning it brings up a page (see attached PDF). This page also has a link to an EPA document. That EPA document relates to ethylene glycol ethers and not silicone base products, so I'm not quite sure what that document has to do with CSSBs warning regarding Dot 5 fluid.

If CSSBs test is accurate (see the PDF attached) it shows quite a bit of swell in the rubber seal.

I really like the idea of Dot 5, i.e. non-hydroscopic and doesn't remove paint, but now I'm wondering if it is wise to use Dot 5.

Is the any validity to CSSBs warning and does it raise concerns with any other Dot 5 users?

Thanks,

Don

[Terry M.]

Re: DOT 5 - Is this new to anyone else?

I used DOT 5 brake fluid when I restored my 66 (non-power), i.e. new lines, rebuilt calipers and rebuilt master. I only have 300 or some miles on the car, but I've been happy with the brakes and had no trouble bleeding the system.

I'm in the process of installing new brake lines on my 67. I also have the calipers off and apart for cleaning and new seals. I will also be taking master cylinder apart for cleaning. This car had Dot 3 fluid in it when I got it. I had an accidental fluid spill at the master cylinder and of course lost paint on the master cylinder, bracket and firewall. Not major just irritating, so I was planning to switch to DOT 5 with all the working I'm doing on the car.

Now here is the rub. I was ordering some parts from Corvette Stainless Steel Brakes and saw a warning on the upper left of their web pages Dot 5 Brake Fluid Will Void Warranty. If you click on this warning it brings up a page (see attached PDF). This page also has a link to an EPA document. That EPA document relates to ethylene glycol ethers and not silicone base products, so I'm not quite sure what that document has to do with CSSBs warning regarding Dot 5 fluid.

If CSSBs test is accurate (see the PDF attached) it shows quite a bit of swell in the rubber seal.

I really like the idea of Dot 5, i.e. non-hydroscopic and doesn't remove paint, but now I'm wondering if it is wise to use Dot 5.

Is the any validity to CSSBs warning and does it raise concerns with any other Dot 5 users?

Thanks,

Don

Don
I presume (is that close to assUme?) you have seen this recent thread:

https://www.forums.ncrs.org/showthre...d-CSSB-Warning

There are many others about DOT5.

[Donald H.]

Re: DOT 5 - Is this new to anyone else?

Thanks Terry, I did not see that thread when I was looking around, but probably because of how I was formulating the searches.

Wow, that thread just adds to my confusion. Has the rubber seals changed, has the formulation of Dot 5 fluid changed, have both changed. What is the real scoop????

Seems to me there is no real resolution and will not be unless someone come across or does some more testing.

Thanks,

Don

[Terry M.]

Re: DOT 5 - Is this new to anyone else?

Thanks Terry, I did not see that thread when I was looking around, but probably because of how I was formulating the searches.

Wow, that thread just adds to my confusion. Has the rubber seals changed, has the formulation of Dot 5 fluid changed, have both changed. What is the real scoop????

Seems to me there is no real resolution and will not be unless someone come across or does some more testing.

Thanks,

Don

I didn't say it would answer your question. It may, however, show that old is better in oh so many ways.

[Joe L.]

Re: DOT 5 - Is this new to anyone else?

All------


Here is what I plan to use on my car. This is a gallon of DOT 5, still factory sealed, that I purchased about 15-20 years ago. This is the DOT 5 once supplied to the US Army by Dow-Corning.

Like others, I find it hard to believe that a brake fluid that is DOT-rated could be incompatible with seals that are also DOT-rated unless the seal manufacturer specifically limits their compatibility to certain DOT fluids. I think that one good way of getting to the bottom of this seal issue would be contacting an automotive brake seal MANUFACTURER (not a re-seller like AC Delco, etc) and getting authoritative information. The Wagner Division of Federal-Mogul would be one such manufacturer although it is possible that they obtain the seals from another manufacturer (one whose name no one has ever heard of as is often the case with some automotive parts).

[Larry M.]

Re: DOT 5 - Is this new to anyone else?

Don:

Based upon my limited research, it appears that SOME DOT 5 fluids currently sold are different composition than what we used years ago. I believe the rubber seals are the same.........regardless of where sourced........USA/Mexico/China.

My recommendation is to contact Stainless Steel Brakes (SSBC, not CSSB) and see if they still sell DOT 5. If so, but it from them. They were the original company that pioneered stainless steel brake sleeving for our Corvettes, and were also a proponent of DOT 5 fluid. I bought my last bottle of their labeled fluid from Corvette Central, so they may still sell it as well. Otherwise call a few of the other MAJOR brake companies and see who still sells and uses DOT 5 in their brake systems (Brembo, Wilwood, etc.).

Like Joe. I have about a quart of the old stuff still left. Not enough for a complete system rebuild, but enough for top-off or flushing. I have flushed my DOT 5 system only one since 1995, and that was when I removed the rear brakes to rebuild the trailing arms on my car.

Good luck.

Larry

[Patrick H.]

Re: DOT 5 - Is this new to anyone else?

My recommendation is to contact Stainless Steel Brakes (SSBC, not CSSB) and see if they still sell DOT 5. If so, but it from them.

Larry

They do:

http://ssbrakes.com/i-10094022-silicone-brake-fluid-silicon-32-oz-a1103.html

It's cheaper from Summit, and there are a few other brands too:

https://www.summitracing.com/search/part-type/brake-fluid?SortBy=Default&SortOrder=Default&cm_mmc=ppc-google-_-search-_-all-part-types-_-keyword&N=4294893829

I'll be working on a 77 this winter that's had DOT5 in it for decades. It needs a new master cylinder to replace the chrome one currently installed, and odds are it will stay DOT5 despite the warning from the repro manufacturer.

[Edward B.]

Re: DOT 5 - Is this new to anyone else?

The warning is appropriate when DOT 5 (silicone) fluid is used in an ABS. Also be advised that a DOT 5.1 fluid is now available which is supposedly an improved version of the tried and true DOT 3 and DOT 4 (non-silicone) fluids. Why DOT chose to confuse matters by using a "5" designation for both silicone and non-silicone based fluids is anyone's guess since it certainly adds a confusion that would not be there if the new non-silicone product had been called DOT 6. Much information is available regarding the non-compatibility of silicone fluid with ABS. Do a search and you will learn more than you ever wanted to know

By the way, a substance that has the ability to absorb moisture from the air is considered "hygroscopic," not "hydroscopic."

[Jim L.]

Re: DOT 5 - Is this new to anyone else?

Ya know, it would really help if someone put on their big boy pants and assembled a brake system with modern seals and modern DOT5 and reported real life results.

[Allen N.]

Re: DOT 5 - Is this new to anyone else?

Ya know, it would really help if someone put on their big boy pants and assembled a brake system with modern seals and modern DOT5 and reported real life results.

If you go to post #2 and click on the linked thread and then go to post #19 you will find a post by Gary Bosselman who had problems with DOT5 and now uses DOT4. His post is as follows:

I quit using Dot 5 fluid probably 5-years ago, maybe longer. I have been care-taker for a persons collection of cars. Most have been sold off now, but he absolutely refused to use anything but DOT 5 fluid. Did not want to hurt the paint. So, about every 12 to 18 months, calipers would start to leak, bring it home, put new calipers on. Good business, especially for the brake people.

The 64, most of the time, would not last 12-months. Every spring, I would take apart the master cylinder, wheel cylinders and put new seals in. The old seals would look like your hands do after being water for a long time. All wrinkled up, swelled up, hard to remove.

The effect of DOT 5 on british cars is even more profound. They leak right away. Usually cannot get it out of the shop into the customers hands.

I was told it was a change in the seal compound, the rubber is not compatible to DOT 5. But, I do not know.

Ever wonder why NO car manufacturer uses DOT 5? I suspect it is more than the cost of the fluid.

I only have one can in the shop. It is an OLD OLD metal can used on Terrys car. It would be fun to have a chemical analysis done, see what has changed.

I use DOT 4 in everything now and do not have any problems. So much for job security?

Gary Bosselman

[Jim L.]

Re: DOT 5 - Is this new to anyone else?

If you go to post #2 and click on the linked thread and then go to post #19 you will find a post by Gary Bosselman who had problems with DOT5 and now uses DOT4. His post is as follows:

I quit using Dot 5 fluid probably 5-years ago, maybe longer. I have been care-taker for a persons collection of cars. Most have been sold off now, but he absolutely refused to use anything but DOT 5 fluid. Did not want to hurt the paint. So, about every 12 to 18 months, calipers would start to leak, bring it home, put new calipers on. Good business, especially for the brake people.

The 64, most of the time, would not last 12-months. Every spring, I would take apart the master cylinder, wheel cylinders and put new seals in. The old seals would look like your hands do after being water for a long time. All wrinkled up, swelled up, hard to remove.

The effect of DOT 5 on british cars is even more profound. They leak right away. Usually cannot get it out of the shop into the customers hands.

I was told it was a change in the seal compound, the rubber is not compatible to DOT 5. But, I do not know.

Ever wonder why NO car manufacturer uses DOT 5? I suspect it is more than the cost of the fluid.

I only have one can in the shop. It is an OLD OLD metal can used on Terrys car. It would be fun to have a chemical analysis done, see what has changed.

I use DOT 4 in everything now and do not have any problems. So much for job security?

Gary Bosselman

Change in seal compound? Well, that's different. The prevailing paranoia has been that the alleged problems with DOT5 have been due to a change in the formulation of the fluid, not the seals.

Don't know what to say...... I've used "old" DOT5 for nearly 30 years with no issues. I even use it in our two road racing cars (because I'm too lazy to bleed the brakes before every track event) and never had a problem.

[Fred Y.]

Re: DOT 5 - Is this new to anyone else?

I'd be interested in some sort of a concrete answer on this as well. Going backwards by using a product that eats your paint if spilled is nuts, HOWEVER my original rebuilt calipers from lonestar say do not use DOT 5. I have yet to add the fluid still, but I certainly would like to find out.

[Tom B.]

Re: DOT 5 - Is this new to anyone else?

It may be a change in the fluid. I guess I'll find out. I just replaced the rear calipers on the '81 that we switched to DOT 5 when it was new. One piston had corrosion under the seal groove but all of the seals still looked like new. The bores had a crescent shaped wear pattern on them but no pitting.

I used the last of my old stock DOT 5 and had to buy some new.

Tom

[Terry M.]

Re: DOT 5 - Is this new to anyone else?

Ya know, it would really help if someone put on their big boy pants and assembled a brake system with modern seals and modern DOT5 and reported real life results.

We all know some people with a strong chemical addiction. If I mentioned their names you would instantly recognize them, however, as far as I know they have all retired from gainful employment in the chemical field. It is too bad because they had access on a daily basis to the equipment to verify the composition of both new and old seals and DOT 5 fluid. It is too bad this issue didn't surface a decade ago. Sic transit gloria mundi

[Timothy B.]

Re: DOT 5 - Is this new to anyone else?

Used a new can of dot 5 in my 67 earlier this year when I rebuilt one rear caliper that was leaking from rotor run out. The brake pedal is normal, I will check the master cylinder level today and report back but everything seems fine.

I will snap a picture of the bottle and post to see if anything jumps out at anyone. I remember reading on the bottle about NOT using the dot 5 product on any ABS system for the reasons we all know and that would explain as Edward points out above why it's not used on new cars.

My feeling is because of the ABS brakes on all new cars that is why the warning is there.