Oh undoubtedly!
Not to mention the saying, “if it ain’t broke, I think I’ll re-engineer it, and spend 10 grand!”
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I’ve always used DOT4 in the car and have been quite happy with it. Someone summarized the advantages and disadvantages of DOT5:
DOT 5
DOT 5 brake fluid is also known as “silicone” brake fluid. It was designed for the US Army, who has requested permission to stop using it.
Advantages:
It does not eat paint or skin.
It does not absorb water (BUT!!! See more on this under disadvantages, below.)
It has a higher boiling point than DOT 3 and DOT 4.
It is compatible with all rubber formulations.
It is a good choice for Concours cars which are rarely driven and/or never driven hard.
Disadvantages:
It does NOT mix with DOT3 or DOT 4 or DOT 5.1. Most reported problems with DOT 5 are probably due to some degree of mixing with other fluid types. A residue of the former non-compatible fluid is sufficient to cause serious issues. The best way to convert to DOT 5 is to totally rebuild the hydraulic system. Additionally, the same advice applies if switching from Dot 5 to any of the other fluids.
Since DOT 5 does not absorb water, any moisture in the hydraulic system will “puddle” in one place. This can cause localized corrosion in the hydraulics.
Careful bleeding is required to get all of the air out of the system. It is hard to you without introducing bubbles and thus results in soft pedal feel. These small bubbles will form large bubbles over time. It may be necessary to do a series of bleeds.
DOT 5 is less compressible (often creating a slightly softer pedal). It is not recommended for racing application.
It is hard to pour without introducing bubbles and thus results in soft pedal feel,
It is not recommended by the brake manufacturer, especially for ABS brakes.
It is about twice as expensive as DOT 4 fluid.
So silicone fluid aerates easily. Harley-Davison, one of the sole current OEM users of silicone fluid, warns buyers to let the fluid sit at least an hour before using it. If shaken on the way home, it will aerate enough to look like a freshly poured soft drink. Silicone fluid is also slightly more compressible than glycol fluid, does not change color to tip the user to its moisture content, and worst of all, neither accepts or disperses moisture, making systems using it more corrosion prone, and requiring much more frequent fluid changes. Silicone brake fluid also lacks glycol fluid’s naturally occurring lubricity, making it incompatible with the mechanical valving in some anti-lock braking systems.
From: Silicone-based DOT5: busting the myth | Mountain Bike Reviews Forum
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Paint, I get: I’ve been coated in DoT 2/3/4, and never experienced issues.
Based on a number of the other observations–and my personal and deep experience, the vast majority of which has been quite favorable–I’ll stick with the old-fashioned, terrible, rotten glycol fluid…
Changed and flushed regularly, mind you!
My results show the opposite, so “YMMV” comes into play.
I’m no mountain bike expert, but silicone is what Moss Motors recommends in our old English cars. I think they are more the experts in our case:
Put another way, brake and clutch systems are designed to be closed, which they are in modern cars. In E-Type systems, Dot 3 absorbs moisture and rusts the components from the inside. Thus, the system is not closed, because water is drawn in from day 1. It was a design shortcoming on Jaguar`s part. Proof of this is they didn’t address it in the owner’s manual.
Silicone fluid, in my experience over 35 years, ensures the closed system, is 100% compatible with the rubber and mechanical components, and thus rust and deterioration are non issues.
This looks like a case of “less is more”.
… as indicated by this direct contradiction in the final paragraph. Doesn’t anyone proof read their articles before publishing any more?
This is what I’ve always understood, which seems to be in direct contradiction of what Tom is saying. The vent on the reservoirs means that our systems are open to the atmosphere, so moisture will get in. I don’t think I’d knowingly get into any vehicle if I knew the brake fluid hadn’t been replaced in 30+ years.
The bottle says the fluid is good for 100,000 miles (see previous post).
Clearly, silicone fluid is NOT hygroscopic. Moisture is not drawn into the system.
Just drove 'er yesterday. Clutch and brakes are as good as they were 35 years ago.
BTW, my 2004 Pacifica will be 18 years old in September. I’m wondering when my mechanic will tell me it’s time to change the brake fluid. I will check the manual and report back.
Also BTW, I’m not recommending anyone ignore their system like I have. My case is simply proof that the results are clear if you do. I haven’t seen any leaks or felt any issues, so I’ve nothing to address.
Clearly, both fluids are regulated and acceptable. And both clearly have a market. To imply one is the answer and the other is not, is, IMO not accurate.
Many years ago, I assume in the 1980’s, I totally rebuilt my brake system and used DOT 5, assuming once and done. I did not touch it for many years. 20+? But eventually, the MC started to get “sticky” and I was tired of the spongy pedal. (After that many years, I would have thought any aeration would have dispersed.) So, although I was satisfied with the life of the fluid, I still went with DOT 4 because of the pedal feel. Also, when I disassembled the components- the fluid was a mess, and it did not prevent all corrosion. I am not saying I would not use DOT 5 again, but I have not. My car, for its early life, was a daily driver, and always stored outside. I certainly will not dispute Tom T.'s success. It may be interesting to know if you (Tom T.) do use your car daily, and is it stored in freezing weather as well as 110F and 100% humidity. Maybe that may make a difference? Also, brake system do not fail only due to corrosion inside the cylinders. Most of my calipers on various cars that are a problem stick because of the dirt on the outside of the seal, under the boot. No fluid helps that, to my knowledge. As to the sleeving, etc, all of my calipers and MC are original, only honed each time. No sleeves.
Again, YMMV, or should I say YMWV- your mileage WILL vary.
Tom
If I had a dollar for every manufacturer’s claim that didn’t pan out. . . . 
I think the bottom line here is one should use what one is most comfortable using. And regardless it makes sense to service the system regularly.
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One thing that’s beingleft out of this conversation is the old bugaboo: humidity.
In dry states, like where I live, this just simply is not the problem that other people have experienced. For example, all the brakes in Tweety were of the original manufacture from 1963 all the way up to the time in 2009, where I finally had to rebuild the master cylinders, the rear brake calipers, at the time that I sold the car in 2016, we’re still the original equipment and worked just fine.
Ditto for Margaret: her brakes are, as far as I know, as-delivered and they’re now 53 years old so the fact of the matter is there are differing Climatic regimes under which these systems all work, and need to be taken into consideration.
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I agree with your assessment, Paul. My car came out of Long Island, NY. Most states on the east coast used salt on the roads in the winter back then. I’m certain this contributed to issues on my four year old car. My first problem was with the clutch slave cylinder. A gas station mechanic honed it out, we dropped some fluid in, and everything was ducky.
Most of my problems were related to a car bordering on overheating in the summer, but that’s for a different thread.
Which is why I refer to this as a ‘Boxers vs Briefs’ topic.
Geo: DOT5 & briefs.
LOL!
Tom: DOT 5 & boxers.
PS: both get dirty, eventually.
Tom, my car is driven regularly in spring through fall, but only when it’s hood down weather, ie, not in the rain. It’s stored in a garage that became heated in 2016. It is not humid in Oregon, but it does get wet, as everyone knows. Interestingly, the humidity in the garage is higher in the summer than it is with winter rains outside.
This is certainly a factor with my results, but note seals and moisture don’t care if the car is running or not. I’ve had to rebuild the carburettors a few times over the years due to ethanol damage, but the brake and clutch hydraulics appear to be in excellent shape.