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Brake fluid change

Posted: Thu May 16, 2019 9:35 pm
by MikeyG
Hey guys,

So I'm guessing the brake fluid in the car hasn't been changed for about 20 years(!!). Its recommended dot 3, however, am I best putting dot 5.1 in purely because its "newer"? I've tried googling it a lot and cant find any good information. I just drive it normally.

Thanks,

Re: Brake fluid change

Posted: Fri May 17, 2019 8:00 am
by jrh
Be careful there.
What was good enough 20 years ago has lasted 20 years.
The 'modern' stuff can contain ingredients which are not compatible with the 'old' components in the system.

Re: Brake fluid change

Posted: Fri May 17, 2019 10:24 am
by Scooby
DOT 3, 4, and 5.1 fluids are found in most brake and clutch systems. DOT 5 is a silicone oil based fluid and can only be used in new, dry systems.

In short, you can put DOT 4 in place of DOT 3 but not the other way around.

DOT 5 is not compatible with DOT 3 and 4 systems.

*Apparently, according to my tame mechanic.

Re: Brake fluid change

Posted: Fri May 17, 2019 11:39 am
by MikeyG
jrh wrote:
Fri May 17, 2019 8:00 am
Be careful there.
What was good enough 20 years ago has lasted 20 years.
The 'modern' stuff can contain ingredients which are not compatible with the 'old' components in the system.
I appreciate that, but I've dipped it with a tester pen and its showing atleast 4% water (the highest reading on the device). I guess its best to change it with DOT 3 to maximise compatibility?

Thanks,

Re: Brake fluid change

Posted: Fri May 17, 2019 12:48 pm
by mojo98
I`ve always used DOT 4, that what the hand book says

Re: Brake fluid change

Posted: Fri May 17, 2019 12:52 pm
by Andy W
mojo98 wrote:
Fri May 17, 2019 12:48 pm
I`ve always used DOT 4, that what the hand book says
That's what I thought. I know we aren't able to use silicone fluid which is a shame as it isn't hygroscopic.

Re: Brake fluid change

Posted: Fri May 17, 2019 1:23 pm
by Kit
Been changing my brake fluid on my cars later,
The old stuff was black, you can see the difference .
Don’t forget to do the clutch ;)

Kit