Jump to content


Welcome to Ultimate Subaru Message Board, my lurker friend!

Welcome to Ultimate Subaru Message Board, an unparalleled Subaru community full of the greatest Subaru gurus and modders on the planet! We offer technical information and discussion about all things Subaru, the best and most popular all wheel drive vehicles ever created.

We offer all this information for free to everyone, even lurkers like you! All we ask in return is that you sign up and give back some of what you get out - without our awesome registered users none of this would be possible! Plus, you get way more great stuff as a member! Lurk to lose, participate to WIN*!
  • Say hello and join the conversation
  • Subscribe to topics and forums to get automatic updates
  • Get your own profile and make new friends
  • Classifieds with all sorts of Subaru goodies
  • Photo hosting in our gallery
  • Meet other cool people with cool cars
Seriously, what are you waiting for? Make your life more fulfilling and join today! You and your Subaru won't regret it, we guarantee** it.

* The joy of participation and being generally awesome constitutes winning
** Not an actual guarantee, but seriously, you probably won't regret it!

Serving the Subaru Community since May 18th, 1998!

Guest Message by DevFuse
 

Photo
- - - - -

Brake fluid DOT 3, 4 and 5.1 question


  • Please log in to reply
10 replies to this topic

#1 1993 Legacy

1993 Legacy

    USMB Regular

  • Members
  • PipPipPip
  • 39 posts
  • Budapest

Posted 02 December 2004 - 01:31 PM

Hello to all,
I was planning on chaning the brake fluid in my car. I have no idea when it was done for the last time as I purchased the car just recently. The fluid in the reservoir looks completely clean (like new).

Now here is the question :)

1993-1994 legacies use either dot 3 or 4, right?

I have read great things about dot 5.1 (mind you that is not dot 5 as that is a completely different fluid). What would be the best way to change the entire fluid in the system?

Go about bleeding it untill ... when?

How much fluid is there in the whole system?

Are there any downfalls if you use dot 5.1 in the car?

Thoughts, ideas, suggestions, procedures are more than welcome.

Thanks to all.
Best regards

Dusan

#2 1993 Legacy

1993 Legacy

    USMB Regular

  • Members
  • PipPipPip
  • 39 posts
  • Budapest

Posted 02 December 2004 - 01:35 PM

Just an addition. I can get some BENDIX SUPER+5 synthetic brake fluidwhich is a DOT 5.1 FLUID. It is reasonablz priced.

It says it meets the requirement of the following specs:

FMVSS 116 DOT 5.1 DOT 4 - SAEJ 1703 - ISO 4925 - NF.R. 12640 S.


What do you say?

Thanks and best regards

Dusan

#3 frag

frag

    Soob shade tree mechanic

  • Members
  • 1,777 posts
  • Montréal, Québec, Can.

Posted 02 December 2004 - 02:28 PM

If the fulid is clear why change it? Usually (like that on my car at least) spent fluid (fluid that has absorbed moisture) becomes a lot darker.
Moreover if you start with clean fluid, it will be more difficult to judge when to stop bleeding cause there will be no color difference between old and new.
Just mu 2 cents.

#4 sasquatch

sasquatch

    USMB is life!

  • Members
  • 230 posts
  • Vancouver

Posted 02 December 2004 - 05:05 PM

If the fulid is clear why change it? Usually (like that on my car at least) spent fluid (fluid that has absorbed moisture) becomes a lot darker.
Moreover if you start with clean fluid, it will be more difficult to judge when to stop bleeding cause there will be no color difference between old and new.
Just mu 2 cents.


brake fluid draws water, water eats metal, eaten metal fouls lines, fouled lines decrease braking, no brakes suck.

#5 Setright

Setright

    Elite Master of the Subaru

  • Members
  • 3,176 posts
  • Denmark

Posted 03 December 2004 - 12:53 AM

Stick with a good DOT 4, like "Castrol Response". You will not be dissappointed, and won't have wasted money on 5.1. The difference in performance is not discernable on the street.
Replace it every 25-30k miles or two years.

#6 1993 Legacy

1993 Legacy

    USMB Regular

  • Members
  • PipPipPip
  • 39 posts
  • Budapest

Posted 03 December 2004 - 03:58 AM

Hi,
The reason to go for DOT 5.1 was that it is less hidroscopic (absorbs less water) and the place where I live is pretty humid.

I have to do it anyhow (it has probably been done sometime in the past but I do not know when) just to be on the safe side just as I am planning on changing all the fluids in the car (to play it safe).

The question is - how much fluid would I need for the whole system (total) ?

How do I go about making sure I have drained all the old fluid?

Correct me if I am wrong but all DOT 3, 4 and 5.1 are compatible. It is only dot 5 that is not compatible since it is of different composition.

Thank you.
Best regards

Dusan
P.S. One leter of the above mentioned DOT 5.1 fluid costs around 12 euros (cca. 14 USD). It doesn't really seem a lot for a procedure which one does once every year or two years, right?

#7 edrach

edrach

    RIP 6/28/14

  • Members
  • 12,326 posts
  • Bothell, WA

Posted 03 December 2004 - 10:00 AM

Another vote for Castrol DOT 4; I live in the Seattle area (can you get much wetter than here?) and have never had to change the brake fluid in it's entirety in any Subaru I've owned over the last 5 years. I've only changed it that way when I've replaced calipers or did the disk conversion on the rear brakes. If you plan on changing it every two years anyway, stick with the Castrol.

#8 frag

frag

    Soob shade tree mechanic

  • Members
  • 1,777 posts
  • Montréal, Québec, Can.

Posted 03 December 2004 - 12:05 PM

If the fulid is clear why change it? Usually (like that on my car at least) spent fluid (fluid that has absorbed moisture) becomes a lot darker.
Moreover if you start with clean fluid, it will be more difficult to judge when to stop bleeding cause there will be no color difference between old and new.


brake fluid draws water, water eats metal, eaten metal fouls lines, fouled lines decrease braking, no brakes suck.


Just wondering: how is this a reply to my post?

#9 Legacy777

Legacy777

    Moderator

  • Moderator
  • 12,566 posts
  • Houston, Tx

Posted 03 December 2004 - 12:53 PM

3, 4, & 5.1 are all compatible and interchangeable. The main difference between the 3 are the wet & dry boiling points & the hygroscopic nature.

Check out this page, it seems to have good info
http://www.vtr.org/m...ake-fluids.html

However, I thought Dot 5.1 was more hygroscopic then 4 & 3.

Either way, a good dot 4 or 5.1 fluid will work fine. If you're not racing, it doesn't matter.

#10 Legacy777

Legacy777

    Moderator

  • Moderator
  • 12,566 posts
  • Houston, Tx

Posted 03 December 2004 - 12:56 PM

brake fluid draws water, water eats metal, eaten metal fouls lines, fouled lines decrease braking, no brakes suck.


Actually, since the fluid absorbs the water and it's suspended in the fluid....it's not really a problem. The added water just lowers the boiling point of the fluid. However, if you boil the brake fluid, the water will then turn into steam, and you now have air & water in the brake system....that is not good.

Dot 5 fluid doesn't absorb water, so pockets of water can move/sit in the brake lines and cause rust like you mentioned.

#11 Hondasucks

Hondasucks

    Subaru Technician

  • Members
  • 4,760 posts
  • Vancouver, WA

Posted 03 December 2004 - 06:56 PM

Just make sure you DO NOT under any circumstances either mix dot 5 (Silicone) and regular propylene glycol brake fluid (they are not compatible) OR run DOT 5 Silicone in a car with ABS! AND if you run DOT5, you must flush your brake system with denatured alcohol (Good idea when changing your brake fluid anyway, to get the moisture out.) You are actually supposed to change your brake fluid every 2 years or 24,000 miles since brake fluid absorbs water, which will lower its boiling point and make your car more prone to brake fade :-)




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users