High temp brake fluid?

[PranK]

In all the track days I've done over the past few months I've only had 1 issue with braking and thats with my current EBC pads (can't remember the colour, but they're not a track pad). I don't *think* I have had issues with brake fluid getting too hot, my understanding is that when that happens you will have quite noticeable brake loss - which I haven't had. 

I'm using just regular ol' Penrite Super DOT4 fluid. I use this fluid in everything and my cars always seem to stop so I see no reason to change, except ... for the 335i. I need to do a fluid flush and was thinking about my fluid of choice and wondering if I should consider using something more high temp? Its not a super fast car by any standards but I'd hate to do a flush and then find myself with no brakes when I get. to Wakefield. 

I guess, my question can be summed up as "How fast do you need to be driving to need higher temp brake fluid?" 

I remember high temp fluid was considered a must have back in the day when I had my GTR. 

[GTSBoy]

That really depends on how hot the brakes get and how much of any heat is transferred into the fluid. That really makes it at least a vehicle specific question, and more than like a specific vehicle specific question, depending on what brakes (ie stock, bigger rotors, different calipers) or even what pads are on it. And then there's the question of cooling air. Is there plenty stock? Is there no special cooling arrangements stock? Has some/more been added?

In other words, I think you have to do the experiment to obtain the data. And if you;re worried - tie on some ducting?

[Murray_Calavera]

I've always approached this as, price is comparable between low temp and high temp fluid. Just put in the high temp fluid.

I've not going to lose any sleep thinking about could I have saved $20 on brake fluid that is going to live in the car over the next 2 to 3 years. 

[PranK]

27 minutes ago, GTSBoy said:

That really depends on how hot the brakes get and how much of any heat is transferred into the fluid. That really makes it at least a vehicle specific question, and more than like a specific vehicle specific question, depending on what brakes (ie stock, bigger rotors, different calipers) or even what pads are on it. And then there's the question of cooling air. Is there plenty stock? Is there no special cooling arrangements stock? Has some/more been added?

In other words, I think you have to do the experiment to obtain the data. And if you;re worried - tie on some ducting?

The brakes are all stock bar some DBA slotted discs and the EBC pads and braided lines. The car has brake ducts as standard but they're kinda pointed in the general direction of the brakes rather than really getting at the heat source. I guess I should hit it with an infra red thermometer after a session and see what they're at. 

14 minutes ago, Murray_Calavera said:

I've always approached this as, price is comparable between low temp and high temp fluid. Just put in the high temp fluid.

I've not going to lose any sleep thinking about could I have saved $20 on brake fluid that is going to live in the car over the next 2 to 3 years. 

100%! Its just a curiosity more than anything. As I said, high temp brake fluid was such a track day rage back in the day. From people I speak to at the track and threads on here everybody has their own take on it but I'm not gonna scoff at spending a few more bucks. 

[PranK]

49 minutes ago, GTSBoy said:

That really depends on how hot the brakes get and how much of any heat is transferred into the fluid. That really makes it at least a vehicle specific question, and more than like a specific vehicle specific question, depending on what brakes (ie stock, bigger rotors, different calipers) or even what pads are on it. And then there's the question of cooling air. Is there plenty stock? Is there no special cooling arrangements stock? Has some/more been added?

In other words, I think you have to do the experiment to obtain the data. And if you;re worried - tie on some ducting?

The brakes are all stock bar some DBA slotted discs and the EBC pads and braided lines. The car has brake ducts as standard but they're kinda pointed in the general direction of the brakes rather than really getting at the heat source. I guess I should hit it with an infra red thermometer after a session and see what they're at. 

36 minutes ago, Murray_Calavera said:

I've always approached this as, price is comparable between low temp and high temp fluid. Just put in the high temp fluid.

I've not going to lose any sleep thinking about could I have saved $20 on brake fluid that is going to live in the car over the next 2 to 3 years. 

100%! Its just a curiosity more than anything. As I said, high temp brake fluid was such a track day rage back in the day. From people I speak to at the track and threads on here everybody has their own take on it but I'm not gonna scoff at spending a few more bucks. 

 

OH, a quick side question - would you use brake fluid from an opened container even if the lid has been on? Eg, if you have a bottle that you opened last time you flushed, it's been tightly closed, is it still good? 

[soviet_merlin]

51 minutes ago, Murray_Calavera said:

I've always approached this as, price is comparable between low temp and high temp fluid. Just put in the high temp fluid.

I've not going to lose any sleep thinking about could I have saved $20 on brake fluid that is going to live in the car over the next 2 to 3 years. 

Does the high temp fluid degrade any different over time compared to normal one? That's one thing I've always been wondering. Because a track car is going to get the fluid flushed probably way more often than every two years and will see less kilometers driven. I would think the requirements are different.

I'm running Motul RBF 600 in mine. Was recommended by my mechanic before a trackday and I've stuck with it since. Hasn't seen the track since but I've kept buying and using it for servicing anyway.

[GTSBoy]

Well, back in the day..... "race" fluids, which were essentially only really "high temp" fluids, used to absorb water more readily. So they really needed to be changed more often anyway. The coincidence of that being directly necessary along with it being what racers would do as a matter of course was just fine.

[Duncan]

Yeah that is still true AFAIK.....good brake fluid should be changed annually because it absorbs water faster which is more often than most mechanics would do it. There are cheap tools that check water% in brake fluid if you all scientific about it.

I for sure would (do) run good brake fluid in anything that even casually saw the track like Murray said; avoiding the risk of "exciting" fade is worth it

[Murray_Calavera]

21 minutes ago, soviet_merlin said:

Does the high temp fluid degrade any different over time compared to normal one? That's one thing I've always been wondering. Because a track car is going to get the fluid flushed probably way more often than every two years and will see less kilometers driven. I would think the requirements are different.

 

3 minutes ago, Duncan said:

Yeah that is still true AFAIK.....good brake fluid should be changed annually because it absorbs water faster which is more often than most mechanics would do it. There are cheap tools that check water% in brake fluid if you all scientific about it.

Just checking, when we are talking about high temp fluid, are we all referring to DOT 5.1?

I haven't had any issues with changing it every 2-3 years. 

[Duncan]

Interesting....can't say I've ever checked it, have always just changed it in the off season as practice

[joshuaho96]

1 hour ago, Murray_Calavera said:

 

Just checking, when we are talking about high temp fluid, are we all referring to DOT 5.1?

I haven't had any issues with changing it every 2-3 years. 

Not sure why but RBF660/700 or Castrol SRF is listed as DOT4, not 5.1.