Dot 5 Fluid and CSSB Warning

[Mark E.]

Re: Dot 5 Fluid and CSSB Warning

Mark —- You are not appreciating the full implication of the non-hydroscopic property of silicone brake fluid. Water gets into brake systems because the regular hydroscopic brake fluid draws water into the system through the rubber brake lines. If you start with a dry brake system and use silicone brake fluid you will never have water in your system and you will never have rust. My 70 Corvette was used in some silicone brake tests by NHTSA in the early 70’s before silicone brake fluid was approved and designated DOT-5. I did not touch the brakes until about 2000 after the fluid had been in the car for about 25 years. The lip seals had taken a set and started to weep. However there was zero rust in the original non-sleeved calipers. I am sure my car is the only 1970 Corvette with the original calipers without sleeves and without rust. Do dot dismiss silicone fluid as unsuitable for 63-82 Corvettes. It does have a slightly spongy petal because of its compressibility but it is the best fluid for these cars and it poses no risk to expensive paint jobs. I would use nothing else.

Patrick,

My post shares Duntov Motor's view, not mine. I thought their advice about DOT 5 (don't use it because it quickly promotes rust) would be of interest since it differs so much from the experience of some (including you). Duntov Motor is a company that builds and prepares Corvette vintage race cars and has a good reputation in the sport. With that said, I don't doubt your positive experience. The mixed results discussed on this thread is baffling.

[Jim L.]

Re: Dot 5 Fluid and CSSB Warning

Patrick,

My post shares Duntov Motor's view, not mine. I thought their advice about DOT 5 (don't use it because it quickly promotes rust) .

That is total toro poo! I've run DOT5 for 40 years in my ancient cars and NOT ONCE have I found a speck of rust in the systems.

Good Lord......

would be of interest since it differs so much from the experience of some (including you). Duntov Motor is a company that builds and prepares Corvette vintage race cars and has a good reputation in the sport.

Eeeeeyeah. They also have another reputation among ethical folks.

The mixed results discussed on this thread is baffling

No it's not. Anyone who has a problem with DOT5 fluid didn't properly convert their brake system to it.

My vintage racer and my bride's road racing track car both use DOT5 fluid and neither car has ever (EVER!) had a brake issue.

Jim

[Larry M.]

Re: Dot 5 Fluid and CSSB Warning

Do not believe everything you read on various websites. That from D Motors is total bull.....

We have discussed this topic quite a bit here and on CF. Most of my replies are at CF in the C1/C2 Section. You can go there for additional info. I discuss both the fluid as well as the rubber brake compounds.

Do not discount what Jim and Pat and Terry and Joe have stated and experienced. You can add me to that list also, but I do not put myself in that group of experts.

Larry

[Owen L.]

Re: Dot 5 Fluid and CSSB Warning

My '67 has had stainless calipers and DOT5 since the late-'80s and (i hate to admit this but...) it's never been changed. Every year or so I check the master cylinder and the fluid is still clear purple and up near the top of the reservoirs; the brakes are not leaking anywhere; the pedal is high and firm; the car stops very well. I'm at the point that I'm afraid if I do something to the system it'll all go to hell, so I leave well enough alone.

When my '72 gets back on the road this coming summer it'll have new stainless calipers, new lines, new hoses, and DOT5. The old DOT4 that was in it during its 30 year storage since the mid-90s completely crystalized and rusted out the system. I know I'm tempting fate using DOT5 according to current thinking and advice but we'll see how it goes.

[Terry M.]

Re: Dot 5 Fluid and CSSB Warning

Mark
Interesting you brought this thread back to life at this time. I am about to have this discussion with several BFFs regarding a car that has spent almost all its life as a "garage monument" (as my wife so lovingly putts it), and is likely to spend many more years languishing in glorious slumber. It does, however, need brake work.

From my experience, and studies, I can tell you that some of what you posted (and I understand you are quoting others) is true and some of it is bravo sierra. I will not go into separating the two again. We have beat this horse to death. I think we are at the point where most all of us have made up our minds and nothing will change them. That situation is not uncommon now days.

I really wish it was settled, but alas the misunderstandings go on....

I can't resist one thing, and this is not a matter of grammar. It is a matter of the meaning of words, and being sure of what others are saying and meaning.: The word is hygroscopic.

https://www.google.com/search?sxsrf=...sclient=psy-ab.

And here is the other example = hydroscopic:

https://www.google.com/search?sxsrf=ALeKk01m-i6_IvzOk9Fp5jsug9pE_A5BkA%3A1611456848019&source=hp&ei=T-EMYJHQOpGQtQW94bzQAQ&q=hydroscopic+vs+hygroscopic&oq=hydroscopic&gs_lcp=CgZwc3ktYWIQARgBMgwIIxCxAhAnEEYQ-QEyBQgAEJECMgcIABCxAxAKMgQIABAKMgQIABAKMgQIABAKMgQIABAKMgQIABAKMgQIABAKMgQIABAKOgkIIxAnEEYQ-QE6BAgjECc6BAgAEEM6CwguELEDEMcBEKMCOgcIABCxAxBDOgoIABCxAxAUEIcCOgUIABCxAzoHCAAQFBCHAjoCCABQwBJY_jBgpocBaABwAHgAgAGNAYgBzQmSAQQwLjExmAEAoAEBqgEHZ3dzLXdpeg&sclient=psy-ab

[Patrick H.]

Re: Dot 5 Fluid and CSSB Warning

If you go to (or stick with) DOT5, I would suggest using O-rings in your calipers.
As I note early in the thread my success with lip seals a couple of years ago was poor when combined with DOT5.

The irony remains that the rear calipers never leaked

Terry, do you have DOT5 left from the old days? If not, I still have plenty and you’re welcome to it.

[Frank D.]

Re: Dot 5 Fluid and CSSB Warning

"Semantic antics" aside I've just not felt a compelling reason to switch from DOT 3 - ever...
Yes, it requires a bit more maintenance, and, if you're an idiot it'll burn through your paint, but its never let me down.

[Harry S.]

Re: Dot 5 Fluid and CSSB Warning

Paint. Last fall I drained the entire system, replaced the hoses and wheel cylinders then proceeded to fill the system with DOT 4. User error, I happened to get the DOT 4 on the wiper grill and part of the surround. I wiped it off immediately, flooded the area with water and cleaner. No affect on the paint. It's a single stage black urethane. I was amazed there was no damage.

[Larry M.]

Re: Dot 5 Fluid and CSSB Warning

Here's an interesting wording change; I don't know what, if anything at all, it amounts to. The yellow warning label shown early in this thread stated that there 'will' be adverse effects. This label says there 'may' be adverse effects:

IMG_3392.jpg

Larry

[Frank D.]

Re: Dot 5 Fluid and CSSB Warning

Paint. Last fall I drained the entire system, replaced the hoses and wheel cylinders then proceeded to fill the system with DOT 4. User error, I happened to get the DOT 4 on the wiper grill and part of the surround. I wiped it off immediately, flooded the area with water and cleaner. No affect on the paint. It's a single stage black urethane. I was amazed there was no damage.

Not to stray off topic, but educate me on DOT 4 - is it fully compatible with DOT 3 (e.g. can I just start adding it to the M/C?), what are its advantages, etc..

[Harry S.]

Re: Dot 5 Fluid and CSSB Warning

Not to stray off topic, but educate me on DOT 4 - is it fully compatible with DOT 3 (e.g. can I just start adding it to the M/C?), what are its advantages, etc..

As far as I know it's the same as DOT 3 but, it has a higher wet and dry boiling point. You can add DOT 4 to a DOT 3 system. You can not add DOT 3 to a DOT 4 system.

[Terry M.]

Re: Dot 5 Fluid and CSSB Warning

I have some old stock (Does that qualify as NOS? ) but not enough to do the job -- actually two jobs. My need will require me convincing Elrod to go against what he believes is his better judgment. Do you want to be a fly on the wall for that?

[Jim L.]

Re: Dot 5 Fluid and CSSB Warning

Not to stray off topic, but educate me on DOT 4 - is it fully compatible with DOT 3 (e.g. can I just start adding it to the M/C?), what are its advantages, etc..

It's completely compatible with DOT3. It just has a higher dry boiling point. Wet boiling point may be higher also. Don't know.

[Jim L.]

Re: Dot 5 Fluid and CSSB Warning

As far as I know it's the same as DOT 3 but, it has a higher wet and dry boiling point. You can add DOT 4 to a DOT 3 system. You can not add DOT 3 to a DOT 4 system.

????

Sure you can. But if you do, you lose the advantage of having had the DOT4 in the system.

[Harry S.]

Re: Dot 5 Fluid and CSSB Warning

????

Sure you can. But if you do, you lose the advantage of having had the DOT4 in the system.

U B correct. I should have said should not add DOT 3 to.......