taikowaza

will be getting the marlin brake pads this week and thanks to a lot of good advice I will not be spending the big bucks on vented slotted rotors, braided brake lines, new shoes and drums etc. I learned that stock 4runner brakes are pretty good, and that rear shoes don't really need replacing all that often.
I also learned that a brake fluid flush can do wonders for pedal feel.
my question is about the best brake fluid to use for a complete flush. going with synthetic redline engine oil and royal purple xfer case and diff fluid was great and I am glad. I'm not finding a lot of information about synthetic brake fluid though, except an old confusing post about DOT 4 and 5 and 5.1 that I did not understand. Thanks for the name of the best brake fluid and how much I'll need, I'll buy it this week!

taikowaza

hmmm just did some searching outside of YT and discovered that synthetic brake fluid might not be a good idea after all, something about 'chunking' and lumixing with old fluid etc...
although some people recommended very high quality fluid with high boiling points.
-------------------------------
(example)

You might want to do some research before you go with a synthetic! I remember something about synthetics. Dont think you can use it!

I used 2+2 Super High Performance 450 F fluid. It works VERY VERY well! I know this because I did not get any brake fade for the first time while towing my 5,300 pound boat!

You dont really need to go synthetics! Just use a very high quality fluid. Change it every year or two and you'll be fine.

CJM

Always used plain old DOT 3 or 4 fluid depending on the car at our shop, no issues.

86tuning

For the most part, regular DOT3 will work fine fine fine for your application.

On a track car (read: racetrack speeds and excessive brake usage and temperatures) you could benefit from a higher temp brake fluid. DOT4 or any of the Super DOT4 brake fluids will work fine. The creme de la creme of super DOT4 fluids is Motul RBF600 which stands for racing brake fluid, 600F boiling point.

On my track car (modified ae86 corolla) I use either RBF600 or DOT5.1 which are both compatible with regular DOT3 and DOT4.

On my truck, I use Toyota DOT3 which is more than sufficient, considering that most of the time the brakes are being used it's going 2mph. Sometimes when I'm driving on the freeway I'll be doing 55mph and a few moderate stops don't even come close to taxing the DOT3 brake fluid boiling point.

The real skinny with brake fluid is that the moisture capacity of a brake fluid effectively decreases with temperature rating increase. So for the most part a DOT4 fluid will hold less moisture than a DOT3. This is not a good thing. On a racecar, it's not a big deal, we do brake maintenance before and after (and sometimes during!) a track session. On a trail rig, you're not likely to do brake maintenance more than once or twice a year.

I would suggest you stick with a regular DOT3 fluid (Toyota fluid works fine) and do a suck n fill of the reservoir once a year. Just get a dollar store turkey baster, and LABEL it BRAKE FLUID so that it doesn't get used for anything else.

As long as the fluid is clean and light yellow, it will work fine. Murky fluids should be flushed out.

Be aware that a neglected system with dark brown or black brake fluid may need more than a simple flush. You may need to overhaul the calipers to get rid of the corrosion inside. And your brake master can actually fail during the bleeding process (but if it does then it was mostly dead anyways).

Now if you're still set on changing brake fluids, you can use any of the following:

DOT3
DOT4
Super DOT4
DOT4 Racing
DOT5.1

The only fluid you absolutely cannot use is DOT5 which is silicone fluid and is NOT compatible with regular brake fluid.

Hope that answers some of your questions.

Cheers!

toyotatom93

Man that answered questions I never even knew I had.

taikowaza

yeah me too thanks 86tuning!!! looks like I'll use Toyota DOT 3. Last question- how many bottles should I pick up from the dealer to do a full fluid replacement?

PCE91V64x4

I use synthetic fluid, DOT 4, in a gray bottle. I think it is valvoline but I am not sure. If I recall, it is $7 for the large bottle. Anything (except DOT 5) is better than what is in your truck right now if the fluid has not been changed in a while.

MMA_Alex

dot 4 doesent hold nearly as much water before you start to run into serious issues. best bet is to go with regular dot 3, and just bleed regularly.

It doesent take that much to flush out the old stuff. i bled my brakes and tried to get most of the old stuff out, and didnt even use a whole bottle.

ps. a vacuum brake bleeder is an awesome investment...

84sr5yoty

Go to a Honda dealership and buy their brake fluid. Unlike all other DOT 3 brake fluids, it's NOT hygroscopic (attracts and absorbs water). Your fluid and rubber brake components will last much longer.

Matt16

My understanding is that brake fluid absorbes the water that somehow gets into the lines thus preventing corrosion. I don't know how water would get into the lines though..

abecedarian

thread resurrection alert!!! lol
glycol based brake fluid is hygroscopic, meaning it absorbs water from the atmosphere so the water gets in through the vent in the master cylinder cap.