The DOT 5 fluids are better in a number of ways but the incompatibility is a real problem. To change over you have to flush the system out with alcohol and it is probably best to do this with all new parts. With just a little bit of maintenance the DOT 4 fluids work just fine. There are resons the auto industry hos not gone the DOT 5 route. 

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of C. Abney
Sent: Wednesday, June 29, 2016 9:34 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Sticky brakes

I didn't read enough into it, but I wonder if the silicon-based brake fluids draw less water.  They are incompatible with the glycol-based ones, but I suppose if you fully flushed the system it would be usable even in the venerable vanagon?

On 6/29/16, Dennis Haynes <d23haynes57@hotmail.com> wrote:
> Brake fluid (glycol) is used as it gets along well with certain 
> rubber/plastic parts. Yes it can absorb moisture especially since most 
> of the system is exposed to ambient temperature changes and it not 
> heated except at the calipers or pistons to drive the moisture out. 
> Worse is that our vans have open caps to let air in as the fluid expands and contracts.
> Year ago many vehicles had a master cylinder with a cover and bladder 
> over the fluid. As the fluid level went down the bladder would pull 
> down with so fresh air never entered those systems.
>
> In reality bakes should be inspected at some regular basis, at least 
> once year or after any unusual situation such as an emergency stops or 
> long term storage. At that point it is not a big deal to flush through 
> some of the fluid. Same for power steering fluid. Some of that 
> darkness could be from the rubber hoses or just from the moisture 
> making the fluid cloudy. Changing it every two or three years will 
> make most issues go away. Still, even with fresh fluid overheating the 
> brakes to the point that the fluid gets to the vapor point will cause 
> a low pedal next application. At that point there can also be caliper 
> or cylinder damage so simply bleeding the brakes may not be sufficient.
>
> Dennis
>
>
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On 
> Behalf Of C. Abney
> Sent: Wednesday, June 29, 2016 7:21 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: Sticky brakes
>
> The properties of brake fluid make it a frequent topic of discussion, 
> and you know it makes me wonder just how much or little thought has 
> been put into its continued use.
>
> Brake fluid absorbs water from the environment.  This water then 
> causes corrosion in the system, brake fade when the brakes get hot, it 
> might increase dissolved gases in the fluid.
>
> I've never seen old brake fluid bled out that wasn't filthy.  Where's 
> that from?
>
> What is it about brake fluid that makes it indispensable to a braking 
> system?  Isn't just about a certain level of viscosity?  If that's so 
> can't something better be substituted for it?
>
> That said, there is a wide variation in the wet/dry boiling points of 
> brake fluid.  Even within one DOT rating.  The vanagon uses dot 4, but 
> dot 5.1 can also be used and is compatible with dot 4, and has a wet 
> boiling pt. MINIMUM of 180C.
>
> For some reason the high boiling point stuff, even though it's the 
> same chemistry as dot 4 in general, is much more expensive.  You're 
> better off being diligent about changing your brake fluid regularly.
>
>
>
>
> --
> There's no .sig like the present
>

--
There's no .sig like the present