Is there a difference between DOT 3 and 4 brake fluid?

[TerryMason]

The guys at Jiffy Lube told my wife that her brake fluid had "dangerously high levels of copper". So, I'm going to change the fluid.

The Honda manual says use DOT 3 fluid. I have a bottle of Valvoline DOT 3 & 4 synthetic fluid. Does this sound like the right stuff to you guys? I've read elsewhere that there is no such thing as synthetic brake fluid and that 3 and 4 are the same stuff.

I don't mind buying new fluid if it's the right thing to do, but I don't want to just waste money.

 

[JPNinPA]

The risk of running different fluid is the fluid eating the gasket and seals.
If it says 3 only use 3.

Another issue is once you open a bottle, it starts absorbing moisture. That lowers the boiling point and leads to sponge brakes.
What year honda?


JPNinPA
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[TerryMason]

2006 Honda Pilot

I'll go get some new DOT 3 fluid - it's cheap anyway.
I've got new pads all around, rotors in the back and fluid change to do before going out of town tomorrow.

 

[JPNinPA]

Being you are getting new you could siphon out 90% of the reservoir then add all new to the reservoir.


Regards,
JPNinPA

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[dusterdude]

Dot 4 has a higher boiling point than dot 3.many import cars come oe with dot 4.nothing wrong with it at all

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[JPNinPA]

I skipped over the Jiffy Lube and "dangerously high levels of copper".
Interesting!!!
Moisture yes. Copper where could it come from?

My 03 states either. Being i had a spongy pedal i looked into it. I ended up fully changing out DOT for DOT 4 and it wirked. But i noticed it got cloudy within a month or so. I changed it again and placed a new reservoir cap on and it was better but i still have some sponginess. No air in the system, so i may be replacing some rubber components soon.

JPNinPA
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[TerryMason]

I skipped over the Jiffy Lube and "dangerously high levels of copper".
Interesting!!!
Moisture yes. Copper where could it come from?

As relayed to me from my wife:
The mechanic had a test strip that he dipped in the brake fluid reservoir. It alerted him to high levels of copper
"You see ma'am, your fittings and connectors are made of copper, and once brake fluid gets old it loses it's corrosion inhibiting properties, and those fittings start to break down. What can happen is that the copper breaks down and becomes loose, and can clog your brake line - then the clogged line gets over pressurized and can rupture causing you to loose all braking ability"

 

[TerryMason]

On a side note, Advance also sells DOT 5 brake fluid.

 

[JPNinPA]

Thats an interesting story. I didnt know steel brake lines are braised and lined with copper.

Also do not use DOT5 unless it is specified. Do not mix DOT5 with any other DOT level.
There is a lot of good info on bob the oil guy site.

JPNinPA
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