[Healeys] Brake Fluid - connect the Dots

[Editorgary at aol.com]

In a message dated 10/19/11 12:48:24 PM, healeys-request at autox.team.net
writes:


> Are these compatible?  Can I mix the two?
>
> Price Lindsay
>
> 630-841-6300 Cell
>

Price,
In a pinch, you can mix Dot 3 and Dot 4 brake fluid. Here's a quick and
accurate summary from the Internet: (jimsgarage.wordpress.com)

"What are those things in the title?   Brake fluid is categorized as one of
those three ratings.   Most brake fluid that comes in a new car will be
rated DOT 3.   A few will Use DOT 4, and very few will ever use DOT 5 which is
a silicone based product.

"If you want to look at brake fluids from a chemical standpoint DOT 3
fluids are based on glycol and glycol esters.   DOT 4 fluids are much like DOT
3
fluids, but also contain borate esters.   There is another rating called DOT
5.1 that consists of borate esters."

However, as a general practice, once you open a can of brake fluid, unless
you're very careful to seal it back up again carefully, you don't want to
use it again, since the open can will absorb moisture like crazy, losing its
effectiveness. In any case, beyond what's written above, Dot 4 is better than
Dot 3, and should be relied on if you can't find Dot 5.1 -- typical brand
Castrol GT-LMA. We won't get into the silicone vs glycol/ester debate here.
Suffice it to say that unless you know you've got a silicone -- DOT 5 --
brake fluid in the system already, you should never add that to the system.

G.