Brake fluid question

Jeb Brookshire · **Posted:** Wed Jan 05, 2011 10:13 pm

My old Volvo calls for DOT 4 fluid. I have some synthetic fluid here that says it exceeds DOT 4 standards. Is it ok to combine that fluid with the existing, even though the current fluid is not synthetic? I suppose I could just bleed the old out and replace it with the syn. Just trying to avoid the extra work.

JamesMilko · **Posted:** Wed Jan 05, 2011 10:49 pm

DOT 5 fluid for sure can't go into a DOT 3/4 system. I'm unsure about DOT 5.1.

DOT 5 fluid will do bad things to the seals in your brakes as it's silicone based instead of glycol based..

Stephen Westerfield · **Posted:** Wed Jan 05, 2011 10:56 pm

Jeb Brookshire wrote:

My old Volvo calls for DOT 4 fluid. I have some synthetic fluid here that says it exceeds DOT 4 standards. Is it ok to combine that fluid with the existing, even though the current fluid is not synthetic? I suppose I could just bleed the old out and replace it with the syn. Just trying to avoid the extra work.

I'd suck the reservoir out as much as you can with a turkey baster and then fill and bleed. You should be fine. What fluid is it?

BretLuter · **Posted:** Wed Jan 05, 2011 11:16 pm

yes, "synthetic" is not the same as "Silicone".

As long as it says it's DOT4 approved, then it's OK to use

JamesShort · **Posted:** Wed Jan 05, 2011 11:34 pm

All brake fluid is synthetic and they love to advertise it

.

5.1 can be mixed with 3/4 but don't mix 5 with anything but 5.

JamesMilko · **Posted:** Wed Jan 05, 2011 11:37 pm

Somehow I missed the DOT 4 part of the post. That is fine to use. It's been a long day.

Sean O'Connell · **Posted:** Wed Jan 05, 2011 11:55 pm

it wont damage the braking system but if it were me i would flush the lines completely not just bleed the calipers. while it wont do any harm i dont like the idea of having two different formulas in my brake lines.

Stephen Westerfield · **Posted:** Thu Jan 06, 2011 9:57 am

Sean O'Connell wrote:

it wont damage the braking system but if it were me i would flush the lines completely not just bleed the calipers. while it wont do any harm i dont like the idea of having two different formulas in my brake lines.

That confuses me. I flush/bleed til I see clean fluid. How would you know if you were just flushing the caliper? Do people do that?

THSCC Forums

Brake fluid question

Who is online