[1 AKY]

Car is due for a brake fluid change and I'm thinking of taking the opportunity to use a higher grade from the standard DOT 4.0(?). Any suggestions as to brand and grade?

[willhollin]

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

[m1bjr]

Motul RBF600.

Have used it extensively on road and track.
Ideal at the price point.

[parapaul]

Hmmm.

How do you use your car, and what other upgrades have you made to the braking system?

For normal road use, there is absolutely no benefit using anything other than bog standard DOT4 from the nearest motor factor.

If you track it, if you've upgraded to braided hoses, if you've got upgraded pads/discs/calipers and you expect to reach the point of brake fade, then you should think about using DOT5.1 instead.

The main difference is the boiling point of the 2 types - DOT5.1 has a higher boiling point, but for normal road use this is almost completely irrelevant

[1 AKY]

many thanks to all the above for their input.

I know i should RTFM!!! but does anyone (off the top of their head) know how flluid much is required?

[willhollin]

If a dealer does it will need 1 litre.

If it is done properly around 3 litres to flush it all properly.

[m1bjr]

Originally Posted by parapaul

Hmmm.

How do you use your car, and what other upgrades have you made to the braking system?

For normal road use, there is absolutely no benefit using anything other than bog standard DOT4 from the nearest motor factor.

If you track it, if you've upgraded to braided hoses, if you've got upgraded pads/discs/calipers and you expect to reach the point of brake fade, then you should think about using DOT5.1 instead.

The main difference is the boiling point of the 2 types - DOT5.1 has a higher boiling point, but for normal road use this is almost completely irrelevant

Not correct.

DOT ratings and boiling point do not go hand in hand.

Motul RBF600 is DOT 4 fluid.
dry boiling point of 312 °C / 593 °F
wet boiling point 216 °C / 420 °F

Motul DOT 5.1 fluid
Dry boiling point 270 °C / 518 °F
Wet boiling point 185 °C / 365 °F



In my experience with tracking road cars, you can overheat old 'cheap' fluids easily.
You can easily get to this point in on the road, mountian passes whilst on holiday come to mind...

I have always found soft pedal (fluid boiled) sets in before I feel 'hard pedal but no brakes' - characteristic of overheated friction material.
A soft or sinking pedal from overheated fluid normally won't recover and needs bleeding.
New fluids will survive better than 12m old stuff in any case, hence the manufacturers 24m reccommendations.

Anyhow, given the relatively small price premium of something akin to the RBF600 DOT4 (+£10) I would not bother with less in a powerful, heavy car.
Just my 2p.

You can flush quite easily with 1ltr of fluid.
Just empty the reservior to within a few mm of the pickup so you dont pull air unneccesarily.
The top up and bleed each corner. I did mine again recently.

[BGM]

Originally Posted by willhollin

If a dealer does it will need 1 litre.

If it is done properly around 3 litres to flush it all properly.

can anyone expand on this?

what is properly, and what is it that a dealer does?!

[Dr Dave]

A stealer will attach a pressure bleeding device to the master cylinder and set it going - the monkey will then raise the car on ramp and open each bleed nipple in turn and will allow an "amount" of fluid to drain into a bleeding pot.

All depends how the tech does it and how much care is taken.

A full bleed which will require diagnostic kit to be hooked up to the car which will fire the ABS solenoids etc will take far more fluid, but is rarely if ever done.

[BGM]

Originally Posted by Dr Dave

A stealer will attach a pressure bleeding device to the master cylinder and set it going - the monkey will then raise the car on ramp and open each bleed nipple in turn and will allow an "amount" of fluid to drain into a bleeding pot.

All depends how the tech does it and how much care is taken.

A full bleed which will require diagnostic kit to be hooked up to the car which will fire the ABS solenoids etc will take far more fluid, but is rarely if ever done.

any way to tell which way it has been done after the event?