The Stovebolt Site Forums The Shop Area Driveline Silicone Brake Fluid DOT type 5

Has any one used this type fluid? I am currently working on a stainless steel tubing upgrade to my brake lines & will be refilling the system soon.

I have read that this type fluid is recommended for trucks that tend to sit for long periods.

Also how much mixing of the Type 3 fluid & type 5 is acceptable? I'll bench bleed the MC but you never get it fully empty.

Thanks

Mixing brake fluids is not recommended (when type 5 is one of them). In fact, it is not recommended to allow rubber parts that have been in contact with type of brake fluid to be used with another type of brake fluid (when type 5 is one of them).

Search in this forum on +brake +silicone. You'll find a lot of opinions and some useful web-links that might have correct and helpful information.

I would advise avoiding DOT 5. As mentioned, it is not compatible with DOT 3 flud, and there are also issues with compatability with the rubber components in a system meant for DOT 3. The silicone in DOT 5 can soften and even destroy the the rubber in the system. It's also not good if you get it on bare steel that will wequire painting. I have personal experience with it, seemed to be fine, until I noticed a puddle under the truck. At first, I thought "oil leak", buth when I checked, it was the master cylinder. Ended up replacing the rubber parts and swapping to DOT 3 (after consulting with the manufacturer), and have had no problems since. Leave DOT 5 to the Harleys and the British car guys.

As long as you change it out annually, brake parts will last a very long time with Dot 3/4. Don't go too long. I changed out the brake fluid this month on my wife's 2004 Honda and it was already quite discolored after just 4 years. I'm not going to let it go that long again but I hadn't had to do a brake job on it yet.

There's been lots of debate over brake fluid changes. The OEMs currently do not advise doing brake system flushes, but the aftermarket disagrees. As far as that goes, we test the fluid for copper content, then suggest wheather or not to change it from there. We usually suggest it at around 200-300 ppm copper content.
However, with the older trucks having vented master cylinders, more frequent flushing is a good idea, as the fliud will ablsorb moisture.

I have had Dot 5 fluid in my 37 pickup truck since 1980. I have recently upgraded to a dual master cylinder. I've had no problems. I know several other locals who have used Dot 5....no problems. I've read about problems, but I'm about to conclude that most of the writing about Dot 5 being bad is writing about Dot 5 being bad. I love it! Clean, no mosture content, easy to use, will not remove paint from other truck parts. True, you do not want to get it on a part you later wish to paint. Paint won't stick to silicone.
Joe

I am using DOT 5 fluid with all parts totally new on my 54 Suburban (standard brakes) and have had no problems in 4+ years.

However, I probably will not do this again with my other trucks; I'll simply thoroughly bleed my brakes once a year and use regular brake fluid.

i have used dot 5 in my 1960 mga for over 25 years with no problems. pedal is a little mushy but not a problem. the main reason was after sitting in storage for the winter the dot 3 would be gone and i had a hard time getting it home.

Thats because your MGA leaks ALL fluids like all early British cars marking their spots. Seriously, just do a search on DOT 5 vs DOT 3. There are good things about DOT 5, however it doesnt like most of the seals out there and it will cause them to swell and loose durometer. You just have to get the correct seal material for DOT 5.

here are the search results http://www.google.com/custom?domains=www.stovebolt.com&q=DOT+5+brake+fluid&sitesearch=www.stovebolt.com&sa=Search&client=pub-3699152422294193&forid=1&ie=ISO-8859-1&oe=ISO-8859-1&cof=GALT%3A%23008000%3BGL%3A1%3BDIV%3A%23336699%3BVLC%3A663399%3BAH%3Acenter%3BBGC%3AFFFFFF%3BLBGC%3A336699%3BALC%3A0000FF%3BLC%3A0000FF%3BT%3A000000%3BGFNT%3A0000FF%3BGIMP%3A0000FF%3BFORID%3A1%3B&hl=en

I've been running DOT3 in my '46 since '86. Sleeved the master cylinder in '97, and just rebuilt it in '08 because of a leak. MC bore was fine, the rubber parts just got old and needed replacement. I bleed the system about every 2 years until I've cycled out all the old fluid. DOT3 is hygroscopic (absorbs water) so it will become contaminated over time and, if left alone, can cause rust problems inside your brake lines where you can't see them.

David Bush

Here, read this http://www.babcox.com/editorial/bf/bf40142.htm I have used synthetic brake fluid in at least two total rebuilds, and will continue to do so.

Interesting article. I still would not advise using DOT 5 unless you are absolutly certain that the rubber components are certified for use with it, as most for domestic vehicles are for DOT 3 and 4 only. To my knowlege, EIS was the only company that made DOT 5 compatible rubber for older vehicles, and they are no longer in business. Wagner does not reccomend DOT 5 with any of their products, with the exeption of vehicles that called for it as original equipment.

OK it looks like we are equally split on using DOT 5 brake fluid. Thanks for the articles & google searches. Although I am replacing my brake tubing with stainless, I am not sure that the other components (wheel cylinders, calipers, Master cylinder) contain the correct rubber types for DOT 5.

I looks like I'll need to go to a regular schedule of fluid change out. Can anyone recommend an easy to use, lower cost vacuum type bleeder?

I'm just curious as to why Dot 5 is not safe with some rubber parts of cylinders. Silicone itself is usually friendly to rubber of all kinds. Does anyone know what the problem is? After reading the article, it seems cost is a major factor. I don't consider that a factor.
Joe

check with your local FLAPS, many have vacuum bleeders for a small deposit.

I myself took a MC cover and hooked fittings to it. I use a large funnel hung from an 8' step ladder with a piece of 1/2" PVC. Gravity fed and near free. A bit messy though

If it's used with non-compatible systems, it can actually make the rubber swell far too much, and in some cases, even make it turn to a gel like gooey mess. It's not so much the silicone itself, but rather the other ingredients that are in it.

Ive heard the same about dot 5, eating into the rubber components that were not made for it. I was really surprised when I bought a few new wheel cylinders for my COE and they were rated for either dot 3 or 5. I havent seen that before on older replacement parts.

Typically you might have one component in the system that is not compatible, such as an old hydrovac, and as such, I wouldnt go that route. If you have any question about dot 5, do not use it.

Another thing Ive heard happen is that if your brake booster gets screwed up internally, it can suck fluid into the engine due to the vaccum used to activate it. Dot 3 burns, dot 5 burns leaving sand. Not good in any engine.

There are two things you dont screw around with, brakes and steering. So if theres any question about it, walk away.

Jeff

Have you noticed that no one on this post using DOT 5 has reported any problems with it? The one person reporting problems with leakage was using DOT 3.

Twenty five years ago I switched my '57 Belair to DOT 5. I didn't know anything about it except it didn't damage paint. I had a rear wheel cyclinder go bad. I rebuilt the wheel cyclinder, drained the fluid and refilled with DOT5. No replacing of the old rubber, no flushing the system, nothing. The brakes still work great.

A few years ago at a Classic Chevy convention, there was a seminar on brakes by one of the major brake manufacturing companies. When the guy finished his one hour presentation, he asked if there were any questions. I asked about DOT 5. He told all the urban legends about it harming rubber parts etc. When I asked about some verifaction, he had none. After further questioning, he told me that his company didn't make DOT 5.

That's because if they made DOT 5 they wouldn't sell nearly as many brake parts. I hear that Harley Davidson and Corvette use DOT 5. If it is good enough for them, it is good enough for me.

Found this on Mid America Auto Works website. "Certified DOT 5 Corvette Silicone Brake Fluid helps prevent corrosion because it does not absorb moisture. It also lubricates and preserves hoses and seals" (Did you catch the part about preserving rubber parts?)

wildbillscorvete.com says "The latest advances in brake fluids are the DOT 5 synthetic products. North American is a leading manufacturer, producing quart bottles of high quality silicone brake fluid. DOT 5 does not absorb moisture like the DOT 3 & 4 products available at the local parts store. This means that your system, particularly if it sits for long periods of time, will not corrode from lack of use. You don't need to start with a brand new system, a thorough bleeding of your existing system with silicone fluid will extend the life of your lines, calipers, wheel cylinders and master cylinder.

DOT 5 Silicone brake fluid is not some exotic chemical strictly for the professional racer, it can and is used in all systems except ABS... it simply is a better, high tech solution for your brake system.

Key Benefits
Non corrosive - doesn't absorb moisture
Protects brake lines, master cylinders and calipers
Won't deteriorate rubber seals and other parts (did you notice the part about Won't deteriorate rubber seals and other parts ?)
Lasts a lifetime
Won't harm painted surfaces if accidentally spilled"

I found this on harleyalaska.com "
DOT 5, is silicone based and does not absorb moisture and does not damage paint. DOT 5 should not be used in any vehicle with anti-lock brakes. The silicone based fluids tend to froth and cause tiny air bubbles when pumped excessively, thus the non use in anti-lock brakes. DOT 3& 4 are hydroscopic meaning they absorb moisture over a period of time. Moisture will cause corrosion in the master and slave cylinders in time if not flushed and replaced at proper recommended times or mileages. DOT 3 & 4 will eat your paint very quickly if left in contact with a painted surface. An open can of DOT 3 or will absorb moisture out of the air very rapidly"

So you decide. I'll stick with DOT 5. I will use it in all my cars until someone can prove to me that there is a problem with it.

Thats the issue. There are about 761 million types of rubber, give or take a few. It comes in every grade imaginable. Some can take gas or solvents while others will gel into nothing in no time flat when exposed.

So the ultimate question is to know whether or not your seals are compatible between the different products available.

Look at it this way- If it would damage a seal, I guess I'd rather a seal leak slowly than a rusted steel line bursting while trying to stop on the highway.

I'm the one that posted about a leakage problem, and it was with DOT5 in the system. after replacing the rubber and going to DOT3 as suggested by the brake parts manufacturer (Wagner), I have had no problems since. Also, GM does not reccomend use of DOT 5 in Corvettes, especially the late models, as it wreaks havoc with the ABS sysems. Thsi also goes for all oems for late model cars. Waht moght be causing the confusion with the 'Vete use suggestion is that they most likely actually mean DOT 5.1, which is not silicone based, but is glycol based and has a higher boiling point (505) than 3/4.
I tried the DOT 5, and had problems, and as a professional brake mechanic, I can really only suggest that one use the fluid that the system was intended to sue, and do the proper maintainace on it.

I'm with Tabasco.
A couple of other points.
Wagner sells, under their label, DOT 5. Harley Davidson sells, under their label, DOT 5.
Again, I and others I know have never had a problem with it.
Here are two reasons why I think allot of people won't use it: First, it is hard to find. You have to want it bad to buy it. Second, it is not cheap! It will run you $20.00 plus a quart.
I think most people don't want to go through the trouble of looking for it and, sometimes, special ordering it. I also think most peole don't want to spend the money for it, when in reality, given the right conditions, it is a good buy and a good investment for the price.
Just my thoughts.
Joe

I'm one more voice for DOT 5. I'm doing a frame off on my '49 1.5-ton (no brake booster). I used regular steel lines (clear coated them after I bent them) all now wheel cylinders and master cylinder. That was 4 years ago. Truck has 1.3 miles on it since. No leaks, no losses, pedal is as firm today as it was after we bled the lines and adjusted the shoes 4 years ago.

I also used DOT 5 on my '39 frame off 15 years ago. No issues then, either.

If there's a problem with DOT 5, I haven't experienced it.

John

Years ago when Dot 5 first came out I put it in a Monte I was driving. I used to think that if something cost more it was better. I ran it for years & had no problems. Ive never used it again because I started hearing bad things about it. Now it seems like in 2-3 years after doing a brake job with Dot 3-4 its all gummed up again. I will probably go back to dot 5 on my next project.

DOT 5 is the onlybrake fluid recommended to be used in Harley-Davidsons. I understand that it has a higher boiling point than other fluids.

Under no circumstances whatsoever should you mix DOT 5 with any other brake fluid, and furthermore I would never use it in any system which had previously had another grade in it, without a total strip and rebuild.

It also seems to be horrendously expensive compared with other grades. Over here in the UK we also have DOT 5:1 which is a totally different fluid to DOT 5.

some info from snowbum's site ....... it should apply to ALL vehicles

Brake fluids:

Use ONLY DOT3 or the slightly better DOT4. Keep it OFF the paintwork, and keep a VERY WET RAG on your paintwork when working with it. If, HORRORS!.. it gets on the paintwork, wash it off with water, INSTANTLY...that means RIGHT NOW! You do NOT have 10 seconds! ALWAYS have a WET RAG instantly available when using brake fluid!

Don't use "race" fluids...they require changing once or twice EVERY year without fail, and offer NO advantages to a street bike. There are so-called 'premium' DOT4 fluids; some are called RACE fluids; and there is also, confusingly, a DOT 5.1 that is NOT silicone based and hence is usable...but WHY?

I recommend inexpensive DOT3 for most folks who want the cheapest, and who do change fluids EVERY year and are not overly hard on brakes, with DOT4 for those who are hard on the brakes, getting them VERY hot. It IS BEST to change brake fluid yearly. I personally do it as part of my pre-Winter service. For longest brake system life, your brake fluid really needs yearly changing, as it attracts moisture, right through the non-leaking lines, molecular sized holes in everything....especially the master cylinder bolt and screw fastenings, etc. Bleed the brakes until clear fluid comes out. Best to use a fresh 8 ounce can each time; but not as much of a must as some say...just don't leave the cap off for appreciable amount of time.

If you regularly change fluid by the full bleeding method, until fluid is nice and clear, then you are UNlikely to EVER have to replace the master cylinder or calipers or brake hoses. If you DO open a system, for such as rebuilding a caliper, or changing a hose, use only brake fluid or specific brake cleaner, for cleaning parts. For very serious caliper overhauls, etc., you COULD use other solvents, heck, even detergent and water...but after drying, any reassembly means using brake fluid for lubrication of parts during assembly, ETC.

In MY opinion, the absolute limit for brake fluid changing for a bike with very MINimal use, is 18 months. Those who ride in a lot of humid weather, or who ride a lot; if the bike is parked in the sunlight, etc., might even consider 6 month fluid changes. Fluid is VERY cheap compared to new parts!


NEVER use DOT 5 silicone fluid in your BMW braking system...NEVER! DOT5 silicone fluid does not absorb moisture, so it allows moisture to condense into droplets in your braking system and thereby probably rotting it out faster; and it can, in freezing weather, FREEZE the brakes! In most situations yearly bleeding will NOT get trapped moisture out of a silicon fluid system. Silicon fluids are also generally not compatible with the rubber parts in your bike's braking system (depending on year of seal manufacture, and if Brembo or ATE). DOT5 silicone fluid has no advantage for airheads. Silicone fluid is thin, so you MIGHT think that it is easier to bleed on an opened system...but, the truth is that silicone brake fluids tend to get millions of tiny bubbles, defeating that idea; and, won't absorb water...but water gets inside from various means, and forms globules, and corrodes the parts! At very elevated temperatures, silicone gets compressible!.....a BAD thing. Yes, there ARE reports of folks using silicone brake fluid for years in Airheads, with no problems. I suspect that there are various types of rubber parts in the system in use over the years. Brembo themselves has always used 'natural rubber' (per Brembo) that is not compatible with silicon fluid. That is how it probably STILL is. I am unsure on ATE calipers. Best not to be a Test Rider.

Remember: moisture droplets can do REAL FAST damage, but small to moderate amounts of moisture dissolved in DOT3 or DOT4 acts so slowly that yearly fluid changes really do work well! The moisture does NOT dissolve in silicon fluids, it collects in droplets that increase their size slowly, and they can do real nasty damage.

Good Tutorial Jim,
Thanks!...I ran DOT5 in my harley just cause they said so.
but never in my vehicles, always use DOT3 with NO PROBS.
got a gallon jug I transfer to 1/4 qrt. squirt bottles for fill ups. etc ..
Tim

I've used dot5 since the birth of my 51 in 2000.works fine for me.replaced lines & wheel cyc everything on the resteration..the military, this is all they use.for things setting aruond for long times.have a friend who got me a gal of DOT5.THAT SAVED ME A FEW $$$.You get NO moisture.ALL THE DOT3 HAS TOO BE BLEED FROM THE BREAK SYSTEM.DONOT MIX 3&5.It may cost a bit more but in the long run you;ll be happy.Check out David Bush reply above its 1000% true

Guys, a few years ago I bought Valvoline dot 3 and 4 SYNTHETIC brake fluid. It's properties seem about the same as Dot 5, but the bottle says it will harm paint, but it is compatible with all dot 3 and 4 fluids, and can be used in ABS systems. So, why not use synthetic 3 & 4 fluid instead of dot 5?