Matt RX8

I'm thinking of swapping my DOT3 brake fluid for DOT4 brake fluid in preparation for some driving schools.

I'm thinking of having the dealer do the work and I provide the brake fluid. Price is quite reasonable.

If I switch to DOT4 fluid, is there any chance that this might invalidate part of the warranty if something should happen to the brake system since the manufacturer recommends DOT3 fluid?

expo1

Timely post, I am going to do the same thing in about two weeks. Since DOT 4 meets the specs of DOT 3 there should not be any problems. Now if I were to brake something doing the change over / bleeding of the brakes then that might be another story. But the fluid itself should not cause any problems. I am also going to change the brake lines to stainless steel, if your going to change to DOT 4 you might at well to the lines at the same time.

takahashi

It is DOT 4 used in Australia - stock! Read the owner's manual. Australian one has DOT 4 in our manual

So I don't see any problem using DOT 4. I use Motul RBF 600 for track as it is DOT 4 based.

Sigma

As long as the fluid (whatever fluid) meets or exceeds the manufacturer suggested requirement, you will have no issues with warranty. Provided, of course, that the manufacturer does not warn against the use of a particular fluid for whatever reason.

airboss

DOT5 would be best. It is sylicone fluid, that does not mix with DOT3 or 4, but is compatible in that it will not mix with or harm it. It is seal compatable. So the system must be fully flushed. It is used in racing, and high end motor cycles.

124Spider

DOT5 is overkill for a long time, and since it requires a full flush, I would not bother. DOT4 will be quite sufficient for his needs for many, many track days. Long before he needs DOT5, he'll want better pads.

BTW, it takes less time to change your fluid yourself than to drive to and from the dealer.

StewC625

I don't know if it's worth it, but if you mix brake fluid with bleach it creates a huge toxic white smoke cloud :D

Matt RX8

Actually I decided to stick with DOT3. My Mazda dealer was pretty adamant about staying with the manufacturer's recomendation. something about viscosity and needing to lubruicate seals in the brake system. probably bs but I don't want to have any issues with the warranty.

I also know a guy in a BMW club that I am in who had some warranty voided for using ATE Super blue. Also my BMW mechanic who preps IT racing cars suggesting sticking with DOT3 until I find that it is not suiting my needs.

So I'm sticking to DOT3 and will change it once per year.

I'm pretty sure the stock setup will be fine for me for a while since I'm a track noob and will only be doing 5-6 days of track work per year. And most of the track work will be DEs where I'll only be doing 25 minute track sessions.

My first event is at Road America which is easy on breaks since it is a long track and the brakes will have ample time to cool.

124Spider

DOT4 includes all protections of DOT 3, and more. It can't void a warranty.

That's pretty shocking, and I'd be very, very interested to know why, since that's what I use in my Honda. There are car manufacturers (Mitsubishi comes to mind) who will void warranties when a car is used on a track, but that's not the same thing as for using DOT4 fluid.

Well, with all due respect, the problem with this advice is that you may find out that it doesn't suit your needs when you lose your brakes at 120mph.

You should be fine for a couple or three track days, but after that, the combination of DOT3 and OEM pads may become dangerous, with pads fading and fluid boiling. Not what I want on the track.

Only if you're a slow learner or if you purposely don't drive hard on the track will you be fine for five track days.

dannobre

iTrader: (3)

DOT3 plus a bit of humidity = no brakes when really hot.

Not worth the risk, or the bit of work it takes to change the fluid.

Change the lines...and the fluid...easy job, and makes a big difference!

JM1FE

I've used ATE Super Blue (Hochleistungsbremsflussigskeit :D) in every BMW I've owned, my VW GTI, a Range Rover, a Jeep... Even BMW dealers sell it (Global Imports in Atlanta, for one), and every decent independent BMW shop I've known recommends it.

I can't begin to imagine what warranty would have been voided by putting ATE Blue in a BMW.