E92 Brake fluid

[I-Mac]

I have an E92 M3 and the brakes die after a good workout.... I was tol that the brake fluid is DOT4 as standard, is this correct?

Anyone know exactly what fluid BMW use in the brakes? I would like to upgrade it to DOT5.1 but don't know which fluid would be safe to use??

Any ideas PH gurus???

[S1MMA]

I would suggest you use Motul RBF600 which is a dot 4 fluid and hence compatible with your braking system. You will be fine with this fluid and will not boil it even on track.

[I-Mac]

Is that better for resisting heat then the standard fluid - it boils in a few laps

Is is a silicone based fluid?

[S1MMA]

It will have a much higher dry and wet boiling point than standard, and is still Dot 4 so you can use it with no probs in your M3. Google it to find temps/specs. I use RBF660 in my Cayman S which has higher boiling points still but is more expensive (and unnecessary unless you are running a race car), Porsche did the fluid change with no probs/questions as it's a Dot 4.

[Teglen]

I had a similar issue on my M6 (fantastic brakes, but fade after a good workout). I changed brake lines (braided), fluid (5.1) and pads (EBC reds)... now they are consistently grippy as hell (and less brake dust too!).

[I-Mac]

What 5.1 fluid did you change to???

[Mroad]

I-Mac said:

What 5.1 fluid did you change to???

Don't get obsessed with DOT 5.1 spec fluids.
Decent DOT 4 fluids will have higher performance specs than most DOT 5.1 fluids.
Castrol SRF is considered the best fluid you can get, is used in top end motorsport and is 'only' DOT 4.
The only reason you need a 5.1 fluid is if your car specifically requires it, i.e. because it needs a lower viscosity to flow through tiny valves in certain ABS systems, the main reason why 5.1 spec was introduced.

I have used Motul RBF600 in all my cars, track and road over the years with no problems. There is now RBF660 with even higher specs (325C dry, 204C wet), both are great performing fluids with the RBF600 good value for money (£22/litre RBF600 against over £40/litre for Castrol SRF).
There are other good fluids out there too, ATE Super Racing Blue (used to be BMW OEM fluid, I've used it before on track) and Castrol Response Super DOT 4 spring to mind with Castrol available off the shelf from Halfords if you're desperate.
All the above fluids are DOT 4.
To work out which is a good fluid you need to look at their Wet and Dry boiling points which are the important performance specs, the higher the temperatures the better. The higher the Wet boiling point the longer lasting the fluid should be (the Wet spec is the boiling point after the fluid has absorbed 5% water).

The most important thing for consistent performance is to change your fluid regularly. The maximum length between changes is 2 years, ideally annually.
If you're tracking the car then changing it before each event is a good habit to get into to avoid any disappointment.

[CarbonM5]

Its not really the fluid thats the problem,although if its more than a year old change it for some dot5.

Try the EBC yellow pads,they are very good but will shorten the life of the disc.

[I-Mac]

Well bought myself some yellow-stuff pads to try out. Considering braided lines and a change of fluid.

Is RBF660 compatible with the seals etc in my E92 brakes?