[Healeys] Brake Fluid

Mon Oct 31 21:03:24 MDT 2022

Notice that earlier forms of Amber and Crimson Castrol Brake Fluid did
not use the word "synthetic" at all. The introduction of that word on
later editions of the liquid revealed the fact that it was not a
natural product, but like todays oils, man made. Were these early
forms DOT 3 or DOT 4 or was this prior to the Dept. of Transports
interference? My 1966 Austin-Healey 3000 came factory equipped with
Castrol Amber. Hank

	-----------------------------------------From: "Christopher Moog via
Healeys" 
To: healeys at autox.team.net
Cc: 
Sent: Monday October 31 2022 7:48:02PM
Subject: Re: [Healeys] Brake Fluid

 That about sums it up.

On 10/31/2022 7:56 PM, Simon Lachlan via Healeys wrote:

	I made myself some notes which I later submitted to our local AH mag.
Here’s the gist of them. May have posted this before…. 

	* “All brake fluid is “synthetic”…it’s not a “natural”
product.
 	* Most synthetic fluids are NOT silicone. They are polyethylene
glycol ether based.
 	* DOT 3 & 4, which can be mixed, are not silicone. They are glycol.
 	* DOT 5, which cannot be mixed with 3 or 4, is silicone. Can’t be
mixed with anything!
 	* DOT 5.1 is glycol based and cannot be mixed with DOT 5.
 	* DOT 5.1 can be mixed with DOT 3 or 4, as both are glycol based.

	The word “synthetic” began to appear when manufacturers worked
out that it made regular brake fluid sound more special ie they could
charge us more money for the same old stuff. 

	DOT stands for Dept. Of Transport and relates to the fluids’
boiling points. If a car brakes at high speed, the brakes get hot.
Some heat is carried away from the brakes by the brake fluid. Bad news
if the fluid boils! The faster you’re going, the higher DOT you
need. Higher DOT numbers indicate higher boiling points for “Dry”
fluid (has not absorbed any water) and “Wet” fluids (has absorbed
water). ie, the wetter it is, the more problematic it becomes. Mixing
3 with 4 lowers the boiling points and vice verca.” 

	Simon 

	FROM: Healeys  ON BEHALF OF Mark Donaldson
SENT: 31 October 2022 22:06
TO: 'Bob Spidell' ; healeys at autox.team.net
SUBJECT: Re: [Healeys] Brake Fluid   

	DOT5 and DOT 5.1 are NOT compatible. 

	I’ve have been using Bel-Ray DOT5 SBF in my BN2 and my tri-carb
since 1992. 

	I’ve never had a problem. 

	Mark 

	Ardmore, NZ 

	FROM: Bob Spidell 
SENT: Monday, 31 October 2022 5:35 PM
TO: healeys at autox.team.net
SUBJECT: Re: [Healeys] Brake Fluid   

	"... There is a newer Glycol Ester DOT5 ..."

 I think you're referring to 'DoT5.1' I also think it was deliberately
named so as to confuse the issue.  

	On 10/30/2022 8:05 PM, Christopher Moog via Healeys wrote:   

	I've used both. Currently prefer DOT4.

 Also everyone is speaking of DOT5 but there are now two different
DOT5s. The first is the older silicone based DOT5. There is a newer
Glycol Ester DOT5 that is compatible with DOT3 and DOT4. It has a
lower viscosity than the DOT3 and DOT4 so it works better in some ABS
systems. It also has a higher boiling point than DOT3 and DOT4. Don't
see an advantage in Healeys.  

	On 10/30/2022 10:00 PM, Alan Seigrist wrote:    

	The best selling point for Dot 4 is you can mix any Dot 4 or even Dot
3 if you need to fill up. As I understand it with Dot 5 you should be
careful to always use the same brand to fill up if necessary.

 Also, neither Dot 5 not Dot 4 is great for sitting a long time, Dot 4
absorbs water, Dot 5 will push any water down into the components.

 Dot 4, if the car is not used regularly, needs to be flushed every
couple of years.  

	On Mon, Oct 31, 2022 at 5:43 AM Michael MacLean  wrote:     

	At this point in the restoration I have a completely rebuilt brake
system with all new components and tubing. Now is the time to make the
decision to use DOT 4 or Silicone. What's the consensus, if there is
one?   

	Mike MacLean   

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