getting ready to bleed the brakes this weekend on my 71. Everything is new, stainless lines, calipers, rear brakes, master cylinder, etc. So should I stick with the ole reliable DOT3 ? Or go synthetic ? Pros, and cons of each ?
I have 2 cars that I switched to DOT 5 Silicone fluid . EVERYTHING had been replaced on both . 69 Electra I did about 35 years ago . I still have the car . The other is my 70 GSX that I did maybe 18 years ago . Both have functioned perfectly . I like the fact that DOT 5 doesn't absorb moisture like DOT 3 and will not harm paint if spilled on it . One problem is bleeding it . You can't shake or agitate the fluid or you will introduce air bubbles in it that are nearly impossible to bleed out . You have to be gentle when pumping the pedal to bleed . Same when you bench bleed the master cylinder . Would I use it again ???? YES if I was replacing EVERYTHING . . The choice is up to you .
Same here, I use DOT 5 whenever I have an all new system. I use it on all my restorations and I put it in my Skylark when I installed the 4 wheels disc. I have seen far too many times what father time can do to a brake system when left in there too long. Dot 3 or 4 may be fine if it is replaced and bled every couple years but who does that?
Ive got cheap dot 3 in everything i own. I know the synthetic stuff is better. However this is one of those upgrades that is simply pissing money away. Dot 3 has been used exclusively in my 66 for nearly 55 years in the original brake lines.. no issues to date with the steel lines. If it ain't broke don't fix it. Dot 3 is fine.
Dot 5 , Great for classic cars that are not driven a lot no moisture issues just change it out every couple years.
There is no need to change DOT 5 fluid every couple of years . It doesn't absorb moisture so there is no reason to change it . Its been in both my vehicles since I first installed it . One car 35 years and the other 18 years . And both cars are driven regularly Now DOT 3 or DOT 4 , Yes you need to change it every couple of years
Not trying to argue with anyone but DOT3 & 4 (Glycol based and both synthetic) absorb water, DOT 5 (Silicone-based and synthetic), does not absorb it but moisture will pool up and may cause localized corrosion. Having said that, I have a friend who has been using it for years with no issues. My DOT 3 I flush out with my Motive bleeder probably every 2-3 years.
That's true John I agree . Moisture can still get into a DOT 5 system and remain separate of the fluid itself . The advantage is the DOT 5 fluid doesn't get degraded by the moisture like DOT 3 or DOT 4 fluid . But as your friend who uses it I haven't seen any issues with using DOT 5 . I don't want to argue either but I have heard the myth that you need to change DOT 5 fluid every couple of years before . Its just not true . I'm sure you know that DOT 5 fluid was developed for the Military for use in damp , humid climates . I would be interested in which fluid your friend used . Silicone based or synthetic ? I know I used Silicone based . My daily drivers use DOT 3 or DOT 4 only because they have Anti-Lock brakes and DOT 5 is not recommended for use in ABS systems . When ever I replace brakes in these systems I purge the old fluid out the bleeders instead of forcing it back to the ABS valves or the Master cylinder . Then I suction out the old fluid in the Reservoir with a baster from the dollar store and refill with fresh fluid . Then gravity bleed till fresh fluid comes from every bleeder . Yeah it takes a while but the result is great . You can feel the difference in the brake pedal . Better that the job that most shops do when they force the old fluid in the calipers back to the ABS valve or the master .
He also had a brand new system (calipers, wheel cylinders, master, lines), so he didnt mix any DOT 3 and 5. Works good for him, I like that of you spill some you don't have to go crazy with worry about paint damage.
I bought my GS in October of 1999. It had silicone fluid in it. It still has the same fluid in it. I check it every so often, still looks great.
