Dot 5 fluid

[edison1970]

Does anyone know if there is a compatibility issue with using Dot 5 in our older brake systems?  I had to put another master cylinder on my car because the seal on the back where the rod goes was leaking . This is the second one.

[cudaize]

I have DOT 5 silicone fluid in (2) of my 71 Cudas and my 70 Challenger and have not had any problems.  I did these when I replaced all brake components as the DOT 5 does not mix with the DOT 3.  If your system has fluid in it you can bleed it out.

The only problem that I have seen is that the silicone fluid ruins the brake switches that are actuated by fluid.  My father goes through about one every year or two on his 58 Fury.  The switches on E-bodies are mechanical so not an issue.

[71340RT]

I have run Dot 5 brake fluid in my 71 Challenger RT for at least 20 years with no problems and it won't damage paint.

[750-h2]

On a restoration Dot 5 brake fluid is the only way to go. If you have a leak or spill it will NOT harm the paint.

[Jay Bee]

My car's had DOT 5 SILICONE in it since 2011 with absolutely no problems or issues. The master, all the lines and wheel cylinder were replaced first.

[anlauto]

Dot 5 in all my restorations 

[floorit426]

Can you change from DOT 3, to DOT 5, without dismantling your brake system?

[edison1970]

Sounds like the answers I was hoping for.  All of the brake components are new on my car. Maybe just poor master cylinders. 

[mopar jack]

Does anyone know if there is a compatibility issue with using Dot 5 in our older brake systems?  I had to put another master cylinder on my car because the seal on the back where the rod goes was leaking . This is the second one.

No leaks at the back but have had a couple disc brake master cylinders leak internally where the front wheel reservoir(the large one) level would go low and the rear wheel reservoir would go high and start to spill out the top.

[MoparLeo]

Personal/professional recommendation. Never use a rebuilt master cylinder, always a high quality, new unit only. Rebuilt M/C's  regularly fail at a much faster rate than new. It only has to fail once....

[dodj]

Can you change from DOT 3, to DOT 5, without dismantling your brake system?

You need to flush it thoroughly first.

[FSHTAIL]

On a restoration Dot 5 brake fluid is the only way to go. If you have a leak or spill it will NOT harm the paint.

That's what the body shop recommended as well just because of the paint.. 

[GoodysGotaCuda]

Can you change from DOT 3, to DOT 5, without dismantling your brake system?

You need to flush it thoroughly first.

I have read "no, you cannot change."

Something to do with how the seals respond to one of the fluids that they need to be new.

I've not tried it.


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[Rich G.]

I just got my master cylinder back from White Post Restoration's with a installation sheet and a lifetime guarantee but void if using dot 5 brake fluid. So many different opinions on this . The only plus I see is that it won't hurt the paint if you have a leak.

[rocketresto]

Make sure the master is compatible with Dot 5.  Have had several fail here with the "correct" repo drum brake master cylinder.  Know Dot 3 can kill paint but seems like every time we run Dot 5 is either leaks or the master fails.  Only run Dot 3 now.