The M3cutters - UK BMW M3 Group Forum
 

Go Back   The M3cutters - UK BMW M3 Group Forum > Forum Sponsors and Advertisers > Opie Oils



Reply
 
Thread Tools Display Modes
Old 26th November 2010, 11:41 AM   #1
oilman
Site Sponsor
 
oilman's Avatar
 
Join Date: Sep 2009
Location: Redruth / Cornwall
Posts: 729
Car: 2004 clue x5
Default Brake Fluid explained

Brake fluid... Bit of a mystery topic!

To help dispel some myths and for some good solid general info on the mysterious world of brake fluids I decided to contact Millers Oils up in West Yorkshire.

Their Technical Director, Martyn Mann was on hand to give us some useful info below is Martyn's article on brake fluids.

There is a degree of confusion regarding the specification of brake fluid and this article sets out to clarify the situation.

The Department of Transportation (DOT) classifies brake fluids to defined specifications. These specifications relate to their boiling points and chemical composition, both of which are important. All currently available brake fluids are covered by one of the following specifications; DOT3, DOT4, DOT5 and DOT5.1.

The laws of thermo-dynamics dictate that the energy from motion is turned into heat through friction. A braking system only works efficiently if the fluid remains incompressible. If the brake fluid boils, it turns to gas, which is compressible and the braking system becomes spongy or in extreme cases fails completely.

A brake system is not perfectly sealed and moisture can get into the system and be absorbed by the fluid. The effect is to reduce the boiling point of the fluid, which reduces the efficiency of the braking system, as described above.

The DOT specifies two reference tests for brake fluids.

* Dry boiling point - the boiling point of fresh fluid

* Wet boiling point the boiling point once the fluid has absorbed moisture (representing brake fluid after time spent in a real situation).

There are two main types of brake fluids:

* DOT 3, DOT 4, Super DOT4* and DOT 5.1 which are based on poly glycol compounds.

* DOT 5, which are based on Silicone.

Note the two types of fluid are not compatible and must not be mixed in a braking system.

SILICONE BRAKE FLUID (DOT 5)

Silicone based DOT 5 was originally introduced to give higher temperature performance over glycol DOT 4. Silicone fluid also has other advantages, it does not damage paintwork and it does not absorb water.

However, silicone fluid is a poor lubricant and does not lubricate ABS pumps as well as PAG fluids. It is also more compressible than PAG fluids, which can result in a sluggish or spongy pedal. It therefore requires special design considerations in braking systems. Further, because it does not absorb water, any water remains as globules, which can pool in low spots in the system and cause corrosion. This water can vaporise when heated under heavy braking giving a disastrous effect on braking efficiency.

DOT5 fluids are not recommended for motor sport applications.

POLY GLYCOL BRAKE FLUIDS (DOT 3, 4 AND 5.1)

Glycol based DOT 4 fluid is the current mainstream brake fluid, and you will see that the specification is considerably better than DOT 3 which it replaces.

DOT 5.1 has higher specification still and is for fast road and occasional track day use. It has a similar spec to DOT4 for the boiling point (>260) but is a lot lower viscosity @-40C typically 900 centistokes (compared to 1500 - 1800 centistokes for DOT 4 and super DOT 4).

Listed in the table below, are the minimum dry/wet boiling point specifications for each DOT level.

BOILING POINT:
DOT 3 - 205C (dry) / 140C (wet)
DOT 4 - 230C (dry) / 155C (wet)
DOT 5 (silicone) - 260C (dry) / 185C (wet)
DOT 5.1 (PAG) - 260C (dry) / 185C (wet)
Super Dot4 * - 300C (dry) / 195C (wet)
(racing brake fluid)

* Super DOT4: The main difference between DOT 4 and Super DOT 4 is the dry boiling point. Normal Dot4 is >260C whilst Super DOT 4 is more like>310C

With thanks to Martyn Mann - Technical Director Millers Oils.

Cheers

Guy.

Opie Oils
oilman is offline   Reply With Quote
Old 26th November 2010, 07:01 PM   #2
paul46
Achieved official socks
 
paul46's Avatar
 
Join Date: Jan 2009
Location: London
Posts: 11,858
Car: AC Schnitzer e46 m3
Default

nice write up and great info, i have always run a castrol super dot 4 in my race bike. great stuff
paul46 is offline   Reply With Quote
Old 26th November 2010, 08:43 PM   #3
oilman
Site Sponsor
 
oilman's Avatar
 
Join Date: Sep 2009
Location: Redruth / Cornwall
Posts: 729
Car: 2004 clue x5
Default

That's a good fluid for the money, although for track use in cars, sometimes one of the higher spec Super DOT4s are necessary.

Cheers

Tim
oilman is offline   Reply With Quote
Old 21st March 2011, 03:24 PM   #4
daniel782
Wearing official underwear
 
daniel782's Avatar
 
Join Date: Jul 2009
Location: Surrey
Posts: 286
Car: 2003 BMW M3 CAB Colour/Combo : Carbon Black/Black Nappa
Default

TIM What brake fluid would you recommend for my E46 M3 Cab??

I've got uprated Stoptech Discs and pads and Goodridge S/Steel Hoses for fast road, but not much track use.

Thanks
Dan
daniel782 is offline   Reply With Quote
Old 21st March 2011, 03:58 PM   #5
JohnH79
Site Sponsor
 
JohnH79's Avatar
 
Join Date: Jul 2010
Location: Southampton
Posts: 2,283
Car: BMW E46 M3 Coupe / Honda CBR600RR
Colour Combo: TiAg / Schwartz
Default

I need to buy some brake fluid for my BBK. Not sure whether to get the Super Dot 4 or the Dot 5.1. Fast road use and occasional track days. What would you advise?
JohnH79 is offline   Reply With Quote
Old 21st March 2011, 04:54 PM   #6
oilman
Site Sponsor
 
oilman's Avatar
 
Join Date: Sep 2009
Location: Redruth / Cornwall
Posts: 729
Car: 2004 clue x5
Default

For both of you I'd probably say the same thing. Motul RBF600, Millers 300 Plus or Fuchs Pro Race are the top choices, Motul DOT 5.1 is a cheaper option.

http://www.opieoils.co.uk/c-450-brake-clutch-fluid.aspx

Cheers

Tim
oilman is offline   Reply With Quote
Old 21st March 2011, 05:14 PM   #7
daniel782
Wearing official underwear
 
daniel782's Avatar
 
Join Date: Jul 2009
Location: Surrey
Posts: 286
Car: 2003 BMW M3 CAB Colour/Combo : Carbon Black/Black Nappa
Default

Thanks, just ordered the Fuchs Pro Race
daniel782 is offline   Reply With Quote
Old 22nd March 2011, 03:26 PM   #8
JohnH79
Site Sponsor
 
JohnH79's Avatar
 
Join Date: Jul 2010
Location: Southampton
Posts: 2,283
Car: BMW E46 M3 Coupe / Honda CBR600RR
Colour Combo: TiAg / Schwartz
Default

Hi Tim, is it just as cheap to order through the website or to order with you direct?

I'd like the RBF600 brake fluid. Would 1 litre be enough to replace all the brake fluid front/rear or will I need 2L ?

Regards

John
JohnH79 is offline   Reply With Quote
Old 23rd March 2011, 09:18 PM   #9
newm3luva
Achieved official socks
 
newm3luva's Avatar
 
Join Date: Jul 2010
Posts: 629
Car: 2002 M3 PY
Default

Hi, what is recommended for standard setup?
Is castrol response DOT4 ok to use? Also how much is needed for a full bleed and refil? Is it 2.8litres?
newm3luva is offline   Reply With Quote
Old 29th March 2011, 06:39 AM   #10
adz2k10
Achieved official socks
 
adz2k10's Avatar
 
Join Date: Jan 2010
Posts: 807
Car: M three
Default

ordered
adz2k10 is offline   Reply With Quote
Old 23rd July 2012, 06:06 AM   #11
RyanC
Achieved official socks
 
RyanC's Avatar
 
Join Date: Mar 2010
Location: Doha,Qatar
Posts: 832
Car: Nada
Default

Quote:
Originally Posted by newm3luva View Post
Hi, what is recommended for standard setup?
Is castrol response DOT4 ok to use? Also how much is needed for a full bleed and refil? Is it 2.8litres?
Did you find the answer to this mate?
RyanC is offline   Reply With Quote
Old 23rd July 2012, 10:28 AM   #12
oilman
Site Sponsor
 
oilman's Avatar
 
Join Date: Sep 2009
Location: Redruth / Cornwall
Posts: 729
Car: 2004 clue x5
Default

I think the one BMW use is the React Performance

http://www.opieoils.co.uk/p-742-cast...ake-fluid.aspx

I don't have brake fluid capacities listed, but I'd think it's about 1-1.5L.

Cheers

Tim
oilman is offline   Reply With Quote
Old 15th February 2014, 11:51 AM   #13
SwiftyM3
Achieved official socks
 
SwiftyM3's Avatar
 
Join Date: Oct 2013
Location: Worksop
Posts: 936
Car: 2002 BMW M3
Colour Combo: Phoenix Yellow / Kiwi
Default

Can you pm me a cutters price please on the RBF 600 brake fluid. Correct me if I'm wrong but I think I need 3 liters to replace my old fluid.
SwiftyM3 is offline   Reply With Quote
Old 17th February 2014, 09:27 AM   #14
oilman
Site Sponsor
 
oilman's Avatar
 
Join Date: Sep 2009
Location: Redruth / Cornwall
Posts: 729
Car: 2004 clue x5
Default

Hi

If you use the code M3C when you order, it gives 10% discount, which is the Cutters price. I don't have the brake capacity listed, but 1-1.5L should be enough.

http://www.opieoils.co.uk/p-894-motu...ake-fluid.aspx

Cheers

Tim
oilman is offline   Reply With Quote
Old 10th June 2014, 02:19 PM   #15
Adil
Achieved official socks
 
Adil's Avatar
 
Join Date: Mar 2010
Posts: 2,074
Car: BMW E46 M3 SMG
Default

Hi,

Can you confirm this is the correct brake fluid for BMW E46 M3 Coupe as I will be changing my frotn discs and pads soon. Also how many litres do I need?

http://www.opieoils.co.uk/p-742-cast...ake-fluid.aspx

Is the 20% of all fluids applicable to this item?

Thanks
Adil is offline   Reply With Quote
Old 10th June 2014, 02:33 PM   #16
oilman
Site Sponsor
 
oilman's Avatar
 
Join Date: Sep 2009
Location: Redruth / Cornwall
Posts: 729
Car: 2004 clue x5
Default

Hi

That's ideal for an M3. I don't have the capacity listed, but I would think 1-1.5L will cover it.

We don't have 20% off all fluids at the moment, but you can use the code M3C for 10% off everything.

Cheers

Tim
oilman is offline   Reply With Quote
Old 10th June 2014, 02:48 PM   #17
Adil
Achieved official socks
 
Adil's Avatar
 
Join Date: Mar 2010
Posts: 2,074
Car: BMW E46 M3 SMG
Default

Quote:
Originally Posted by oilman View Post
Hi

That's ideal for an M3. I don't have the capacity listed, but I would think 1-1.5L will cover it.

We don't have 20% off all fluids at the moment, but you can use the code M3C for 10% off everything.

Cheers

Tim
Great,

Thanks for the quick reply Tim. Will order up.
Adil is offline   Reply With Quote
Old 21st July 2015, 09:08 AM   #18
Dalgib
Achieved official socks
 
Dalgib's Avatar
 
Join Date: Mar 2015
Location: newtownabbey
Posts: 947
Car: 2017 M140
Colour Combo: Mineral Grey/Black Dakota
Default

I know this is an old thread, but currently what's the best brake fluid ( fast rd use) for my e46 m3 also is 1.5 ltrs what I need?
Dalgib is offline   Reply With Quote
Old 21st July 2015, 09:46 AM   #19
oilman
Site Sponsor
 
oilman's Avatar
 
Join Date: Sep 2009
Location: Redruth / Cornwall
Posts: 729
Car: 2004 clue x5
Default

The best fluids for the brakes and clutch are the Castrol SRF, Motul RBF660 and Gulf RF1000. The Motul RBF600, Gulf RF800, Millers 300 Plus and Fuchs Pro Race are close to those, but don't have quite as high boiling points. Those are overkill for road use, but can be used on road if you want. The next step down (in performance terms), but still an upgrade over standard are the Gulf Racing 5.1, Motul DOT 5.1 and Castrol React Performance. Any of the other DOT4 fluids we have are fine to use as a standard choice.

http://www.opieoils.co.uk/c-450-brak...tch-fluid.aspx

Yes, a litre and a half should be plenty.

Cheers

Tim
oilman is offline   Reply With Quote
Old 21st July 2015, 12:16 PM   #20
Dalgib
Achieved official socks
 
Dalgib's Avatar
 
Join Date: Mar 2015
Location: newtownabbey
Posts: 947
Car: 2017 M140
Colour Combo: Mineral Grey/Black Dakota
Default

Quote:
Originally Posted by oilman View Post
The best fluids for the brakes and clutch are the Castrol SRF, Motul RBF660 and Gulf RF1000. The Motul RBF600, Gulf RF800, Millers 300 Plus and Fuchs Pro Race are close to those, but don't have quite as high boiling points. Those are overkill for road use, but can be used on road if you want. The next step down (in performance terms), but still an upgrade over standard are the Gulf Racing 5.1, Motul DOT 5.1 and Castrol React Performance. Any of the other DOT4 fluids we have are fine to use as a standard choice.

http://www.opieoils.co.uk/c-450-brak...tch-fluid.aspx

Yes, a litre and a half should be plenty.

Cheers

Tim
Ordered with yourselves thank you for your help ��
Dalgib is offline   Reply With Quote
Reply

Bookmarks


Thread Tools
Display Modes



All times are GMT. The time now is 09:11 AM.


This website uses cookies. By continuing to use the site you are agreeing to our use of cookies. To find out more about the cookies this website uses, click here.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Copyright © 2007 - 2018 M3cutters. All Rights Reserved.