[DML] Re: DOT 5 (was Brake and Clutch bleeding (Was: Transmission))

[Mark Noeltner <mark@xxxx>]

DOT 5 silicone fluids do have some disadvantages. Since they don't absorb
water, it tends to pool at the lowest point in the system, leading to
heavier corrosion (rust) in the calipers or wheel cylinders if the system
is flushed periodically. Silicone fluids also turn compressible at much
lower temps than glycol based DOT 4 fluids, which means that you have a
somewhat "softer" pedal feel. Silicone DOT 5 fluids are generally more
expensive than a good DOT 4 fluid also.

Not putting down DOT 5 silicone fluids, just pointing out the negatives. :)

Personally, I don't feel that they're worth it. I prefer to flush and fill
the systems every two years or less with DOT 4 Castrol LMA fluid.

Mark N
VIN 6820

At 04:53 PM 3/23/00 -0700, Nate Kile wrote:
>I have used nothing but DOT 5 fluid in my Corvettes. Started when I replaced
>the calipers, and disks with Willowood parts. They only guaranteed their
>calipers to extreme temps (350+ degrees) with DOT 5. The DOT 3 or 4 is
>hydrophilic (attracts moisture like a day off) The "funk" that grows in the
>DOT 3/4 and makes it "dirty" is actually algae (no, not the same stuff as in
>your fish pond, but like it.) The silicone base lacks both the moisture, and
>nutrients to feed the plants. (the moisture is also the cause of corrosion
>of the steel parts, furthering the funk in the fluid syndrome) I have since
>replaced DOT 3/4 with 5 in all my vehicles. Some simple warnings though, be
>sure to completely flush the system (denatured alcohol was recommended by
>"Vette Brakes co.") label the damn thing so a half brained girlfriend
>doesn't put dot 3 in the system... they separate faster than Italian salad
>dressing.
>
>(another added plus of dot 5... it's harmless to paint, or our nice epoxy
>frame coating, and cavitates only under the most extreme
>temperature/vibration)
>
>More info is available from willowood, of Vette brakes company (cool sites
>too.)
>