dot 3 brake fluid - getting rare?

[andycook]

trying to find some dot 3 brake fluid for 4runner

halfords - dot 4 and 5.1 only
autoparts place - dot 4 only
garage dot 4

wheres dot 3 gone?!

[Delboy]

Last time i looked in seven places, none had dot 3, so i just threw some dot 4 in. Think its extinct

[andycook]

Did search on web, some sites said it was ok to mix Dot 3 and 4
and others said it wasn't...

all said you cant mix dot 3/4 and dot 5.1

had enough of dots...

[Vagrant No2]

Did search on web, some sites said it was ok to mix Dot 3 and 4
and others said it wasn't...

all said you cant mix dot 3/4 and dot 5.1

had enough of dots...

I would suggest a full system flush and replace with 5.1 . Brake/clutch Fluid should be changed every 3 years due to water absobsion from the atmosphere .
If flushing , start at the furthest corner away from the master cylinder and work your way forward ie nsr , osr , nsf and finally osf . Do not push the brake pedal all the way to the floor , just half way . This is in case worn seals are in the master cylinder and they can collapse . Just keep topping up fluid as you go with new until each corner has bled nice clean fluid through .

Rick

[NiftyNev]

I would suggest a full system flush and replace with 5.1 . Brake/clutch Fluid should be changed every 3 years due to water absobsion from the atmosphere .
If flushing , start at the furthest corner away from the master cylinder and work your way forward ie nsr , osr , nsf and finally osf . Do not push the brake pedal all the way to the floor , just half way . This is in case worn seals are in the master cylinder and they can collapse . Just keep topping up fluid as you go with new until each corner has bled nice clean fluid through .

Rick

Correct me if I am wrong but -

I don't think dot 5.1 fluid is compatible with the seals in brake and clutch systems that recommend dot 3/4 fluid.

Neville

[Vagrant No2]

Correct me if I am wrong but -

I don't think dot 5.1 fluid is compatible with the seals in brake and clutch systems that recommend dot 3/4 fluid.

Neville

I have been informed that once a complete flush of the system is carried out you can use the 5.1 . Some do say that the seals can perish quicker as a result of fluid type change ,but that can happen at any time , with any fliud .

Only my opinion

Rick

[UKWolf]

DOT3 & 4 should be compatable, Dot4 is a higher spec vesion of Dot3 ( I wouldn't mix them though)

DOT5 is a synthetic fluid and is definately not compatable with 3 & 4. DOT5 does not have the hydroscopic qualities of 3&4 and should not affect the seals.

IF you've got the time, patence, and money (a fair bit of fluid is need to fully flush the system), flush though and use DOT5. If you are going to this much trouble I would repalce the slave cylinder seals at least.

[andy]

I found this regarging DOT 5 Fluids

DOT5 does NOT mix with DOT3 or DOT4. Most reported problems with DOT5 are probably due to some degree of mixing with other fluid types. The best way to convert to DOT5 is to totally rebuild the hydraulic system.
Reports of DOT5 causing premature failure of rubber brake parts were more common with early DOT5 formulations. This is thought to be due to improper addition of swelling agents and has been fixed in recent formulations.
Since DOT5 does not absorb water, any moisture in the hydraulic system will "puddle" in one place. This can cause localized corrosion in the hydraulics.
Careful bleeding is required to get all of the air out of the system. Small bubbles can form in the fluid that will form large bubbles over time. It may be necessary to do a series of bleeds.
DOT5 is slightly compressible (giving a very slightly soft pedal), and has a lower boiling point than DOT4.
DOT5 is about twice as expensive as DOT4 fluid. It is also difficult to find, generally only available at selected auto parts stores.





DOT5.1 is a relatively new brake fluid that is causing no end of confusion amongst mechanics. The DOT could avoid a lot of confusion by giving this new fluid a different designation. The 5.1 designation could lead one to believe that it's a modification of silicone-based DOT 5 brake fluid. Calling it 4.1 or 6 might have been more appropriate since it's a glycol-based fluid like the DOT 3 and 4 types, not silicone-based like DOT 5 fluid. (In fact, Spectro is marketing a similar new fluid which they are calling Supreme DOT 4, which seems less confusing.)
As far as the basic behavior of 5.1 fluids, they are much like "high performance" DOT4 fluids, rather than traditional DOT5 brake fluids.

Advantages:

DOT5.1 provides superior performance over the other brake fluids discussed here. It has a higher boiling point, either dry or wet, than DOT 3 or 4. In fact, its dry boiling point (about 275 degrees C) is almost as high as racing fluid (about 300 degrees C) and 5.1's wet boiling point (about 175 to 200 degrees C) is naturally much higher than racing's (about 145 C).
DOT5.1 is said to be compatible with all rubber formulations.
Disadvantages:
DOT5.1 fluids (and Spectro's Supreme DOT4) are non-silicone fluids and will absorb water.
DOT5.1 fluids, like DOT3 & DOT4 will eat paint.
DOT 5.1 fluids are difficult to find for sale, typically at very few auto parts stores, mostly limited to "speed shops."
DOT 5.1 will be more expensive than DOT3 or DOT4, and more difficult to find.

[Vagrant No2]

This is the stuff alot of the guys in my local Club Lotus use in older vehicles and new:


Automec SBF DOT5 .
Rear of carton reads, in breif :It is compatable with the seals and hoses used by all vehicle manufactures except for those few who use mineral based fluids ...
Higher boiling point at 500F then most DOT3 or DOT4 ......and absorbs no moisture ....
Will not damage paintwork ....
To use simply drain system .... bled out with new fluid .....

A general copy of the write up as images provided are marred by camera flash.
I have bought this fluid for my use , when car finished , possibley in another 18 years time . At least I now the shelf life is not affected .

Rick