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EFV-8 Club Forum / General Ford Discussion / Dot 3 to Dot 5

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Posted By Discussion Topic: Dot 3 to Dot 5 -- page: 1 2 3     len47merc 01-20-2017 @ 7:55 AM reply profile send p.m. Senior Posts: 1168 Joined: Oct 2013 Thanks for posting this Tom. Like others on EFV8 I gravitate toward the most objective, data-based processes and products and the science and technology here, at first blush for me, appears reasonable and sound. If one wishes to maximize fluid value and time investment this appears to be a very good solution. Looking at the product description in more detail on their website they also have strips for coolant system corrosion as well. Very interesting. Thanks again - Steve TomO 01-20-2017 @ 7:33 AM reply profile send p.m. Senior Posts: 7386 Joined: Oct 2009 There are test strips to test when corrosion is present in DOT 3, 4, 5.1 glycol based brake fluids. The test have only been done on modern brake systems with ABS, but should work as well in the old cars. The main drawback is that the strips cost (about $5.50 each) more than the brake fluid. There could be savings if you intend to pay a professional to change your fluid, strictly on a time basis of every couple of years. Here is a link to a report on the basis for the strips. The report was paid for by the manufacturer of the strips. http://www.gwrauto.com/stripdip.htm Tom len47merc 01-20-2017 @ 6:30 AM reply profile send p.m. Senior Posts: 1168 Joined: Oct 2013 You're welcome Drbrown and thanks for the reply. One other point I forgot to mention earlier, made by the engineer at the DOT 5 manufacturer, was that the US military strongly prefers to use DOT 5 in all non-ABS applications given DOT 5 '...never needs changing...' (his words) assuming the brake system is a sealed system, no contaminants are ever allowed to enter the system and the components are all properly engineered to be fully compatible with DOT 5. He reiterated that DOT 3, 4 or 5.1 should, in his humble, technical opinion, '...never need changing in classic cars-driven-less than 3,000 miles/yr...' applications excepting for, as mentioned previously, peace-of-mind and/or the most extreme of humid conditions. The 'peace-of-mind' issue, coupled with my the experience with my '61 (albeit with it 2 decades+, irregular 60K+ miles use use without changing) will probably drive me to change the DOT 3 currently in my '47 (~8,000 miles in ~3.5 years on it since full system restoration) in another year or two during a particularly dry/low humidity winter period. With the knowledge gleaned over the last week, the urgency to change it during this winter's partial storage, based on the 2-3 year change-frequency 'paradigm', has abated. Steve This message was edited by len47merc on 1-20-17 @ 6:46 AM Drbrown 01-19-2017 @ 7:57 PM reply profile send p.m. Senior Posts: 609 Joined: Nov 2013 len47merc .... Regardless of what comes out of this thread, I personally thank you for spending the time to investigate the questions raised here. I could have undertaken the same effort but did not. I continue to use DOT 3 in my '47 and so far have not had problems or leakage. If and when it comes to a point where significant parts the entire system need replacement, I would then consider the DOT 5 move. len47merc 01-18-2017 @ 6:11 PM reply profile send p.m. Senior Posts: 1168 Joined: Oct 2013 I hear you 40cpe and if I ever rework this '47's system in its entirety, or do the same on the next project, I'll be right there with you. My comments earlier were not only in support of your reply but also challenging of the paradigms concerning change frequency. I have flushed my Infiniti, Hondas, etc., per the maintenance schedule (always wondered if it was necessary) but have never touched the '90 Burb and it keeps on chuggin'. Conversely, had to completely rework an actively driven '61 Impala SS brake system in the 80's likely because the fluid had never been flushed/changed. Probably not smart on the Burb but it is what it is. I'm 3+ years into the '47 Merc's new brake system and had to do a deep dive on this subject after Drbrown's last question to educate myself on what I should do. Appreciate everyone weighing in. Learned a lot here - thanks to all! Steve 40cpe 01-18-2017 @ 4:51 PM reply profile send p.m. Member Posts: 488 Joined: Jan 2010 Steve, in the early '80s I bought a '57 Ranchero. With working and family responsibilities I would go months or a couple of years sometimes without moving the car. EVERY time after one of these stints I would have a leaking wheel cylinder with DOT 3. I finally had enough and changed all the wheel cylinders, flushed the master and lines, and installed DOT 5. I never had another leak even with the same infrequent use. That is the reason I put DOT 5 in my '40 when I built it. len47merc 01-18-2017 @ 1:25 PM reply profile send p.m. Senior Posts: 1168 Joined: Oct 2013 Drbrown asks a good question. My post was predicated on the assumption I would not 'have' to worry about purging/replacing Dot 5 in my lifetime or remaining ownership of this vehicle, this to better protect the original floormat and brake system componentry as well. This assumption was based on representations made here and elsewhere about the non-hygroscopic nature of Dot 5. Drbrown's question got me to thinking whether Dot 5's service life was in reality any greater or not than Dot 3. Perhaps another attribute of Dot 5 (versus Dot 3's hygroscopic nature) begins to degrade at the same rate as Dot 3. (And given my driving behavior of this car statistically never heats the brakes to the point of perhaps boiling the 3%-5% max water absorbed into the DOT 3, why even worry about it - but those are other issues) So, after a short Dr.'s appt this am I stopped by both CarQuest and NAPA, and in addition to picking up some needed supplies for my modern vehicles, obtained the name-brand manufacturers of DOT 5 and DOT 3 brake fluids. From there I came home and called technical support for two manufacturers and obtained the following key information: 1) It is impossible to purge a brake system of all DOT 3 or 4 fluids and accordingly neither endorsed a conversion to DOT 5 for this reason. DOT 5 was only recommended for all new brake system componentry 2) For classic cars driven less than 3,000 miles/year, driven as most classic cars are, from quite genuine, pragmatic, logical and supportive perspectives both suppliers indicated synthetic DOT 3 likely should never have to be changed except in the most extreme of humid conditions (e.g., Mississippi Delta, Florida Keys, etc.) and even then they both questioned the value in doing such. They both indicated their desire to sell more fluid but practically speaking both indicated the 'need' for purging DOT 3 systems every 2-3 years is more marketing driven than anything. For personal peace of mind it is your choice if you wish to go down this road 3) For all new classic car brake systems DOT 5 can provide longer-term corrosion resistance but the RECOMMENDED change intervals do not vary much, if at all, from DOT 3. In the end, from both manufacturer's technical support Teams, if you are installing a completely new system - master, switch, lines, wheel cylinders, etc., then DOT 5 is the way to go for total peace of mind in a classic car such as our EFV8's (but you will likely have a softer pedal due to soluble oxygen). Beyond that, if you are driving these originals like most of us do, DOT 3 or 4 will do just fine and, unless you so wish to, should never need purging in your ownership of the car unless you wish to do so for peace of mind. According to these guys, by the time any corrosion of adequate significance to affect performance has time to occur in a DOT 3, max 3,000 mile/yr driver system you'll likely be of the mindset for an overhaul anyway. And in support of 40cpe and deluxe40 (albeit DOT 3 specific here), to this date I am still driving an original '90 Suburban - that's a 27 year old vehicle with over 210K miles all here in central NC - with DOT 3, that I've yet to have the need to change the master, calipers and/or wheel cylinders on, that also has never had the DOT 3 changed. Hmmm... FWIW - Steve This message was edited by len47merc on 1-18-17 @ 1:54 PM deluxe40 01-18-2017 @ 10:30 AM reply profile send p.m. Member Posts: 413 Joined: Oct 2009 I put Dot 5 in my phaeton ('32 w/ new '40 brakes) in 1998. Had to replace one brass washer to get a hose to stop leaking at first. Since then I have been driving the car at least once a month with no problems. I also inherited a Model A with '40 brakes and Dot 5 fluid. It had been sitting for eight years after the brakes were rebuilt and I drove it for eight more years after that without problems. 40cpe 01-18-2017 @ 6:36 AM reply profile send p.m. Member Posts: 488 Joined: Jan 2010 Drbrown asked about the "effective" life of Dot5 fluid. In the early '90s I put it in a car I built. I sold the car a year ago with the same fluid, master and wheel cylinders. I live in the humid deep south and this car was driven year round and stored in an unheated garage. Drbrown 01-17-2017 @ 6:50 PM reply profile send p.m. Senior Posts: 609 Joined: Nov 2013 So that begs the question - Looking past the recommendations or requirements of cost-motivated car and fluid manufacturers, what is the effective life of DOT 5 fluid ? Unless there's responsible data, one has to make his own decision. I may have missed it but I don't remember seeing any solid forum discussion about it. This message was edited by Drbrown on 1-17-17 @ 6:51 PM

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