Brake Fluid: DOT4 or DOT3?

[Talasas]

I'm just wondering, Toyota seems to insist on using DOT3 brake fluid. I've been told by several brake shops to not bother and use DOT4. Bleeding the AE92 system today I found the fluid is DOT3 (it's green) and I think DOT4 is blue (does that sound right?).

I've also seen bottle of "Super DOT3" at Motor Traders before. Now I know DOT4 and DOT3 can be mixed (but shouldn't) and that DOT4 is newer. Is there a reason Toyota still insist on DOT3?

and what should I get for simple street use?

[IN 05 NT]

use whatever youve got, it make no difference in a street car,

the colour is just for tracing leaks,..it can be whatever colour the company decides on,
weve currently got yellow, and blue,

[jeffro ra28]

Motul apparently make a DOT5.
anyone else hered this? or maybe its super DOT4?

[MR22ZZ]

there are heaps of DOT 5.1 fluids on the market.

[4agte]

you dont need anything more than dot 4 even for track use really good dot 4 changed regularly i.e every 6 months if you track it or drive spiritedly

also fwiw ive been told by mechanics at toyota that some dot 4's can cause issues with seals in some toyota's but i cant back that up its just what i was told

[Fish]

PBR gold. Around $8 a bottle and its all we ever use in the race car and road car and never had brake fade.

[TERRA Operative]

I use Motul RBF600, it's 5.1 and seems pretty good.

[Hen]

From some background and a bit of reading around.
DOT3 and 4 are similar and can be mixed. Not great, but can be done. DOT 4 has a higher boiling point.
DOT5 is silicone based and different to DOT 3 and 4. Do not mix with them.
DOT 5.1 is most similar to DOT 3 and 4 strangely enough.

Hen

[BigWorm]

So DOT 5.1 isn't silicone based?
I've always wanted to try DOT 5, purely for the non paint peeling properties. Although I imagine it would have a longer service life as it's also not hydroscopic.
Is changing to 5 just a matter of performing a really good flush?

[oldcorollas]

the cans of toyota fluid in Autobacs and Yellowhat here are all dot3....

bigworm, i think you wouldn7t want to have any trace of old stuff in system.. so a clean and dry might be in order perhaps?

[TERRA Operative]

Dot 5 has a tendency to foam under repeated heavy braking. You have to watch the rubber seals too. Some types of rubber don't like the silicone.

[RObErT_RaTh]

The reservoir lid in my MA61 says use DOT3 but I've got DOT4 in there at the moment and haven't had any trouble, feels good for a spirited street car. Was all fresh, I didn't mix.

[Viper]

As stated, DOT3 and DOT4 can be mixed.
They are both similar in make-up, with DOT4 having a higher boiling point.
There is also SuperDOT4, which Holden & Ford use locally.
This is just 'tweaked' DOT4, with higher boiling point again.
I 'think' its a mix of 5.1 and 4.
Holden use Yellow, Ford Blue, but its just dye anyway.
Caltex sell this stuff in a Silver Bottle, with Red/Green stickers.

DOT5.1 again, us higher boiling point then DOT4, and again, similar compound, so it can be mixed, but you loose the benefits, so why would you.

DOT5 is silicon based, and thus non-hydroscopic, I.E. it doesn't absorb water. Most seals int eh braking system aren't designed for it, so its more hassle then its worth.

[TooF]

i run the motul rbf600 not cheap but bloody good. apparently there is a penrite product (psychofox on these forums pointed it out to me) that runs very similar specs the the motul at about a thrid the price.

otherwise the castrol super dot 4 (silver bottle) ivealso used for a long time and always been impressed.

[IN 05 NT]

as mentioned above, dot 5 is purely a race fluid, everything needs to be extensivlly flushed clear, and then all caliper seals need to be replaced, master seals are bit more tolerent(so we were told at the time)

its not cheap either for the pure stuff, $90 a bottle for 500ml, (something outrageuos like that!)
helped a mate do it for his datto 1600 a while ago.