Can I switch to dot 5 silicone brake fluid?

[Cudakiller70]

Does anyone have experience with flushing an existing brake system and using dot 5 silicone brake fluid?

[JH27N0B]

Sure, it's no big deal. Just flush the old brake fluid out with fresh dot 5 until you get pure dot 5 coming out the bleeders. The dot 5 is purple, but strangely I've found that when I filled my virgin brake system that had all new lines and components, the fluid filling the jar as we bled seemed to have lost its purple hue!  It still feels and smells different than regular brake fluid.
Some say to flush out the lines with alcohol before adding dot 5.  I don't like that idea because the alcohol is hard on the seals.  A trace of regular brake fluid still in the system isn't going to wreck the dot 5 fluid.

[GoodysGotaCuda]

I believe it comes recommended to flush with denatured alcohol, I've read that you should try to avoid mixing where possible.

Once you go DOT 5, you must rebuild it all before going back to DOT 3 or 4, however, according to Wilwood. I have DOT5 in my 'Cuda..

[Chryco Psycho]

I would definatly switch , Dot 5 will not hurt paint 
Dot 3 & 4 will mix with water , dot 5 is silicone based , they do not mix dot 5 will float on top of the dot 3-4 so you need to flush it out & the fluid coming out of the top of the calipers will be dot 5 as it will be on top so I would invert the calipers & drain & flush them Before adding Dot 5

[GoodysGotaCuda]

I would definatly switch , Dot 5 will not hurt paint 
Dot 3 & 4 will mix with water , dot 5 is silicone based , they do not mix dot 5 will float on top of the dot 3-4 so you need to flush it out & the fluid coming out of the top of the calipers will be dot 5 as it will be on top so I would invert the calipers & drain & flush them Before adding Dot 5

For the record, wilwood suggested I rebuild all calipers and the master if switching from DOT 5 to DOT 4. I asked when I was having issues bleeding my brakes as 5 tends to want to hang onto suspended air bubbles.


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[Cuda Cody]

I've heard people having mixed success when switching to DOT 5 from 3 or 4.

[GoodysGotaCuda]

I've heard people having mixed success when switching to DOT 5 from 3 or 4.

So far the ability to not worry about my paint has been worth the little more effort it's taken to get DOT 5 "right".


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[b5cuda]

I've been running DOT5 in my '69 cuda for about ten years.  Changed out the fluid once.  No problems with performance.

[Lemontwist]

Yes you can switch BUT you must rebuild all the calipers and master cylinder before switching.  The reason is that regular brake fluid makes all the seals swell.  If you don't rebuild everything the new DOT5 will not work properly.  I know because I had to learn the hard way.