Recent Topics
Picture of M1 High Mileage 5w-30 at work
by Oro_O
8 minutes 9 seconds ago
Walmart Coupons
by Warstud
Today at 09:45 AM
Snow Shoe Info Needed
by larryinnewyork
Today at 07:13 AM
Article on antifreeze and pet poisoning
by schuylkill
Today at 06:43 AM
Carlson Hardware
by greasegunn
Today at 05:57 AM
Dang! Snowblower Wasn't in 2WD for Years
by ronbo
Today at 05:56 AM
Nokian WRG3
by Patman
Today at 05:43 AM
Non linearity in mixing VIIs
by Shannow
Today at 03:23 AM
PPPP 5W20 Test Results ?
by ChrisD46
Today at 03:13 AM
Electric fence load
by mjoekingz28
Today at 01:46 AM
Would there be any negative effects?
by 268i
Today at 01:22 AM
How to kill a Leprechaun
by 285south
Yesterday at 11:46 PM
Newest Members
splatt, Lars65inc, dothedrew1202, dg370, Shuskey4
51982 Registered Users
Who's Online
81 registered (andyd, aa1986, aquariuscsm, 65convertible, 1999nick, 7 invisible), 1837 Guests and 187 Spiders online.
Key: Admin, Global Mod, Mod
Forum Stats
51982 Members
66 Forums
222516 Topics
3521748 Posts

Max Online: 2862 @ 07/07/14 03:10 PM
Donate to BITOG
Page 2 of 2 < 1 2
Topic Options
#3086379 - 08/05/13 10:35 AM Re: Chemistry of Brake Fluids [Re: Garak]
MolaKule Offline


Registered: 06/05/02
Posts: 14699
Loc: Iowegia
Originally Posted By: Garak
Thanks for that. I, too, had heard such a thing mentioned. Of course, it's never something from a company that makes the stuff or in a sourced article. It's just mentioned in passing in some general tech article.


Exactly, inferential information from the Internet is dangerous.
_________________________
My bed is where I suddenly remember all the things I was supposed to do today. smile

Top
#3087147 - 08/06/13 01:48 AM Re: Chemistry of Brake Fluids [Re: MolaKule]
Garak Offline


Registered: 12/05/09
Posts: 11756
Loc: Regina, Saskatchewan, Canada
I blame the German automakers. wink In North America, where everyone specifies DOT 3, few (if any) manufacturers call for a brake fluid replacement interval. The Germans, who tend to call for DOT 4, often do call for a replacement interval. Therefore, there must be something wrong with the DOT 4 fluid, rather than just a different take on maintenance, of course.
_________________________
Plain, simple Garak.

2008 Infiniti G37 coupe - Mobil Delvac 1 ESP 5w-40, Hastings LF113
1984 F-150 4.9L six - Quaker State GB 10w-30, Wix 51515

Top
#3087252 - 08/06/13 07:48 AM Re: Chemistry of Brake Fluids [Re: MolaKule]
tc1446 Offline


Registered: 12/10/10
Posts: 485
Loc: NC
Some brand name cans say "Dot 3/4". I read this as it can be used either way or mixed. right or wrong?
_________________________
'13 Accord EX-L
'00 Ford Ranger {46K}
'14 Can Am SE6 (13K)

Top
#3087726 - 08/06/13 03:52 PM Re: Chemistry of Brake Fluids [Re: tc1446]
jrustles Offline


Registered: 02/24/13
Posts: 2035
Loc: Ontario, Canada
Thanks for the article Molakule!

Originally Posted By: tc1446
Some brand name cans say "Dot 3/4". I read this as it can be used either way or mixed. right or wrong?


Probably, just like motor oils. I personally wouldn't mix exclusively separate chemistries. Mixing different ethers/blends could, as Mola pointed out, change the boiling point of the resultant fluid, and this is where one enters into unknown-spec territory. Compatability-wise, if you had to do it, you could. shrug
_________________________
"No matter how paranoid or conspiracy-minded you are, what the government is actually doing is worse than you imagine" W.Blum

Top
#3087920 - 08/06/13 06:43 PM Re: Chemistry of Brake Fluids [Re: tc1446]
MolaKule Offline


Registered: 06/05/02
Posts: 14699
Loc: Iowegia
Originally Posted By: tc1446
Some brand name cans say "Dot 3/4". I read this as it can be used either way or mixed. right or wrong?


What the label is saying is that it is a DOT 4 fluid with a higher boiling point that can also be used in DOT 3 applications.

Again gentlemen and ladies, let us not compare brake fluid to motor oil or other fluids.

It is a very specialized hydraulic fluid and is hygroscopic which means it can absorb moisture, which means you need to change it every three years or less.

Let me stress again, Brake fluid is a SAFETY ITEM.
_________________________
My bed is where I suddenly remember all the things I was supposed to do today. smile

Top
#3157913 - 10/16/13 04:35 PM Re: Chemistry of Brake Fluids [Re: Tay]
gpshumway Offline


Registered: 06/18/08
Posts: 415
Loc: Minneapolis, MN
Originally Posted By: Tay
i read that DOT 5.1 is much more hygroscopic then DOT 4 and DOT 4 more then DOT 3.

is there any truth to this?


Not necessarily more total absorption for DOT 4, but they tend to absorb moisture at a higher rate. German cars take DOT 4 fluid, but require replacement every 2 years (in general), Asian cars take DOT 3 fluid, but only require replacement every 3 years.

Stoptech has a good white paper on this:
http://www.stoptech.com/technical-support/technical-white-papers/brake-fluid

Originally Posted By: Stoptech
The real differentiating factor is that DOT 4 fluid should be changed more often than a DOT 3 fluid, because of the effects and rates of water absorption.
_________________________
2007 Subaru WRX
2011 Honda Civic EX

Top
#3162635 - 10/21/13 01:10 PM Re: Chemistry of Brake Fluids [Re: JHZR2]
miro Offline


Registered: 05/05/13
Posts: 72
Loc: the Netherlands
Thanks for the huge contribution in this forum.
I really like to read your articles. I like the way how you explain- with simple words expunging such complex area like modern fluid chemistry


Edited by miro (10/21/13 01:11 PM)

Top
#3352601 - 04/25/14 08:52 AM Re: Chemistry of Brake Fluids [Re: MolaKule]
Oldmoparguy1 Offline


Registered: 01/21/05
Posts: 4096
Loc: Charlotte, NC
I've always wondered, why did the auto industry settle on glycol type brake fluid? The aircraft industry uses a petroleum based fluid, at least in my experience. Looks like ATF.

Wayne
_________________________
"Political language is designed to make lies sound truthful and murder respectable, and to give an appearance of solidity to pure wind." George Orwell

Top
#3353381 - 04/25/14 09:46 PM Re: Chemistry of Brake Fluids [Re: MolaKule]
MolaKule Offline


Registered: 06/05/02
Posts: 14699
Loc: Iowegia
I think it was due to five things:

1. Brake fluid system pressure

2. brake line materials

3. seal materials

4. compressibility of comparative fluids

5. flammability and vapors


Edited by MolaKule (04/25/14 09:47 PM)
_________________________
My bed is where I suddenly remember all the things I was supposed to do today. smile

Top
Page 2 of 2 < 1 2