My brake system is all new and empty. I'm running manual disc brakes in front and drums in rear. What fluid are folks using ?
Don't be afraid to use DOT 5 silicone on an "everything new" system, just be prepared to stay with it from here on out...the silicone fluid is not compatible with any others. Benefits: (1) It's not hygroscopic, so it won't absorb water. (2) Higher boiling point. (3) It won't melt the paint off your fender. Devon
I read up on the dot 5 fluid and one brake manufacturer recommends not using it with their systems because they say that when water does get in a brake system with dot 5 fluid instead of being absorbed it tends to puddle in the system which results in more corrosion. I was surprised to read that.
I can understand that, but it begs the question...how would that much water get in? The non-silicone fluids actually try to absorb moisture, silicone does not. A dry, sealed system will go for years and years on DOT 5. Devon
I bought my GS in October of 1999. It has DOT5 in it. I have never had to touch it ever. Still looks great. Not sure how water can get into the system. I suspect whoever told you that just doesn't want you to buy DOT5 fluid. You periodically have to flush DOT3 because it absorbs water. They sell more fluid that way.
Thanks for posting this up! I'm getting ready to do all new brake lines and components on the GS400, with the disc brake upgrade. This reinforces the decision to use DOT 5 brake fluid in it!
You won't regret it . One more tip ! don't agitate the fluid before you use it . If you do you will tend to make bubbles in it and make it a bit hard to bleed . And no rapid strokes of the pedal if you use that way to bleed . Even while and after Bench bleeding the master cylinder . I suggest Gravity bleeding . Rapid and violent pumping of the pedal will tend to add air bubbles .
Dot 5 seems to solve a problem that does not exist. It makes your car faster by making your wallet lighter. Yep, I know the benefits but I reject the doom and gloom of using Dot 3.
Thanks for the tips! I usually gravity bleed when replacing a lot of brake components... from somewhere on my arms or hands, as well as the brake system. Ha ha ha! I also have one of those vacuum pump gimmicks that can help.
Dot 5 fluid is about twice the price of Dot 3 or Dot 4 true . But I would rather spend the extra coin to not have to touch it for at least 20 years unlike DOT 3 or DOT 4 . Which would have cost me 5 times what I spent on the DOT 5 . So actually my wallet is a bit heavier and I am solving a problem that does exist ! I.E. : The tendency for DOT 3 and DOT 4 to absorbe Moisture .
I don't question or doubt dot 3 absorbs moisture but I've also never seen a brake line rust from the inside out... I've also worked on more than my fair share of older rigs and never had a single issue with 20 year old dot 3. To each his own but running dot 5 is an exercise in keeping up with the Jones.
The new Synthetic Dot 3 is much better to resist moisture then the old stuff from my experience and it won't attack paint as fast either. i've used Dot 5 as well, doesn't seem to evaporate as fast as Dot 3 but my reference was old motorcycles with ALOT less volume. I understand Dot 5 can have a lower boiling point and could cause trouble in heavy braking situation. I think this is more related to racing application. I'm no chemist this is simply my experience and what i've read. If it has Dot 3 in it i would leave it.
I am running DOT4 in my car that has the original brake system, and DOT5 in the one that I replaced entirely. Both are great/no problem. If flushing and filling once and a while (5 years?) isn't a problem, DOT3 OR 4 are fine. Then again, if you have the new empty clean system, DOT4 lets you forget it, until it leaks out...
This has turned into PROs and CONs on the merits of DOT 5 Fluid . Do your research and figure out what is best for you . Its not the idea of keeping up with the Jones but rather sticking with the Smiths . If you are contemplating replacing EVERYTHING in the system go with the DOT 5 and never turn back . Otherwise stay with the DOT 3 and service it a few times thru out the years . My modern vehicles have DOT 3 but are flushed every time Pads are replaced . And that dirty fluid is NEVER forced back upstream . . There is a definite improvement to the "FEEL " of the brake pedal and the stopping power . Just my perspective from over 50 years in the business .
