Subject: Re: [Healeys] Brake Fluid

From: Tom Felts <[email-masked]>
Date: Sat, 12 Oct 2013 8:44:30 -0400

I kinda hate to take a counter position, but will anyway--not saying this is the 
best or right thing to do. 
 
YEARS ago I drained the Dot 4 fluid from my BJ8's system----drained it and 
nothing more----and then added silicone brake fluid.  I have since changed it a 
few times  after a few years of use, but all rubber components are the 
same----and---I have never had a problem.  So----I guess you could say draining 
it is sufficient---maybe------at least it worked for me.   What Kees says about water being able to get into the system with silicone is true, so it also must be changed at some frequency----but not as often as DOT4.
 
Tom 
---- Oudesluys <[email-masked]> wrote: 

=============
When new the cars used DOT3 as DOT4 was not available yet. DOT4 is an 
improved DOT3. DOT5 is a silicon brake fluid that is not hygroscopic 
like DOT3/4, however is can not be mixed with DOT3/4 and once a system 
has been filled with DOT3/4 it is not wise to refill the system with 
DOT5 even after it has been rinsed thoroughly. Only if all rubber 
components have been renewed you can use DOT5 safely.
There is another brake fluid DOT5.1 which can be regarded as an improved 
version of DOT4. This does mix with DOT3/4 but not with DOT5.
Use DOT4, any make will do, widely available, cheap and safe. It will 
absorb water so you have to change the fluid every 2-3 years, depending 
on the climate. Because of this you will automatically clean out the 
system periodically
DOT5 hardly absorbs any water, which, if entered, then will collect in 
some low spot in the system and cause corrosion unnoticed. Most people 
think that you do not have to change it periodically because the is no 
water absorption, however there is still wear in the system. It is also 
slightly compressible giving a very slightly spongy feeling. These are 
the reasons I do not like to use it.
A can of worms has been opened again.
Kees Oudesluijs
NL
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