DOT 5 Brake Fluid

[kverges]

I have used DOT 5 in many cars in the past, with no ill effects. It does get spongy with heat, so I quit using it in cars with any track potential. The nice thing is that it is not hygroscopic and won't eat paint like glycol-based fluids. I think you will like it fine for street driving and even autocross, but don't use it on track.

I personally think the horror stories about destroying seals is a bit of a wive's tale, but then again I have used it in only maybe 6 different cars.

 

[JonB]

Old Debate: Short Answer - (SEARCH to find the long answer)

DO NOT USE DOT 5.0 (a silicone) in a Viper.

I know of dealers who mistakenly put DOT-5 in, and after owner complaints were told by Team Viper to flush it out. ESPECIALLY IMPORTANT if you plan ANY track events where brake temps will exceed nomal street temps. Could even be DANGEROUS in damp climates when track events are planned.

Use a good HiTemp Dot 4. or even a Dot 5.1.

Silicone Fluid should NOT be used in a Viper.

 

[Roland L-Ocala FL]

Just had my fluid changed to DOT 5 by the dealer. He feels that it will not hurt anything on the Gen 1 breaking system. Have any of you used DOT 5 and how has it stood up so far? Did you have to change any seals or anything beforehand? They just flushed system and replaced with DOT 5. I don't want to see my rubber seals deteriorate or anything.

 

[Joel]

I'm completely with Jon on this, do not use DOT 5, but do use DOT 5.1, they are totally different. However many people mistakenly call DOT 5.1, DOT 5. Check with your dealer, maybe he has made the same mistake and all is OK.
DOT 5.1 is an excellent fluid which is well on the way to being a comp type fluid with elevated boiling point. Skunk will be recieving this in the next week or two. BTW, compared with full comp fluid DOT 5.1 is quite cheap.

 

[Roland L-Ocala FL]

Looks like it is back to the dealer and a change of brake fluid to DOT 4 for me. Just curious Jon, why would it be more of a danger in wet or damp conditions?

 

[Viper Wizard]

Holly-Smokes!
This time I agree with "jonb". NO DOT 5

[Folks write this one on the wall!

]

[Silicone attracks moisture]

 

[kverges]

I sure would like to see hard data on silicone attracting moisture. I have used the stuff and my experience is completely opposite. How many of you have used silicone fluid?

In fact, some of the really high end DOT 4 fluids are problematic because they are so hygroscopic. They are fine for racing, but that's because racers routinely and frequently change fluid.

I agree that silicone is no good for the track, but on the street it has been fine for me; I use it in my clutch system simply because it is such low maintenance and heat is not a big issue there.

FWIW.

 

[Joel]

My understanding is that DOT 5 (silicone) is very difficult to bleed effectively and almost always some small pockets of air are left in the system leading to a spongier pedal. When the fluid heats up past the boiling point of water the moisture which is inevitably in the air pockets, vapourises, causing an expansion of the gas and leading to an even spongier pedal. I think I'm right here but am open to other criticism. Also I believe that silicone fluid has a compatibility issue with the proportioning valve.
Its probably fine in the clutch hydraulics !

 

[SNK BIT in WA]

I have used the silicone, DOT 5 brake fluid in my Viper youth and LOST MY BRAKES WHILE ON THE TRACK!
Save yourself the change of underwear and go with Motul 6 if you plan on being on the track. Regular DOT 4 if you just drive on the street.

I was on my warm up lap late in the day when I hit 100 mph. Thank God is was not 140 mph like a hot lap. When I pushed the brake pedal to the floor....

Now I use Motul 6 and the brakes have been awesome with no fade or spongy feeling at all.

Mark

 

[JonB]

While all brake fluid attracks moisture, some attracks more. Hygroscopic is the propensity to seek out moisture.

Non-silicone fluids slowly absorb it, and their "wet boiling point" rises accordingly, the pedal reaches sponginess more slowly, and you have a warning of imminent loss of hot brakes.

Silicone however, allows the moisture to pool, and boil MUCH sooner. Little/no absorption. No warning. As Mark saw at Spokane, the LONGEST STRAIGHT in the Western USA, this is a bad time to have no brakes.

The silicone also has other nasty tendencies, and does NOT perform as well in extremes. Proof: NO RACE TEAMS ANYWHERE EVER USE IT! It is a granndma's fluid, who never intends to change or bleed again.

Tacky but memorable: "Silicone Belongs in breasts, not brakes"

--Special Thanks note to the wiz--

 

[Henry Cone]

From Jon B:

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>
Non-silicone fluids slowly absorb it, and their "wet boiling point" rises accordingly, the pedal reaches sponginess more slowly, and you have a warning of imminent loss of hot brakes.
<HR></BLOCKQUOTE>

Actually their wet boiling point DROPS accordingly. Every once in a while I get to correct Jon...