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Adrian Avgerinos
12-09-2004, 08:17 PM
I came across a link, regarding brake fluid, that might be of particular interest to those that do not understand the difference between DOT 3,4,5,5.1.

Shown here:

http://www.vtr.org/maintain/brake-fluids.html



DOT3
DOT3 brake fluid is the "conventional" brake fluid used in most vehicles. One of the most familiar brands is "Prestone."

Advantages:
*DOT3 fluid is inexpensive, and available at most gas stations, department stores, and any auto parts store.


Disadvantages:
*DOT3 will damage natural rubber brake seals and should not be used in any car suspected of having natural rubber seals (most Triumphs prior to 1968).
*DOT3 fluid eats paint!
*DOT3 fluid absorbs water very readily. (This is often referred to as being hydroscopic.) As such, once a container of DOT3 has been opened, it should not be stored for periods much longer than a week before use.
*Since DOT3 fluid absorbs water, any moisture absorbed by the fluid can encourage corrosion in the brake lines and cylinders.

DOT4
DOT4 brake fluid is the brake fluid suggested for use in late model Triumphs. The most familiar brand is "Castrol GT-LMA"

Advantages:
*DOT4 fluid is available at most auto parts stores, and at some (but not all) gas stations or department stores.
*DOT4 fluid does not absorb water as readily as DOT3 fluid.
*DOT4 fluid has a higher boiling point than DOT3 fluid, making it more suitable for high performance applications where the brake systems are expected to get hot.

Disadvantages:
*DOT4 fluid eats paint! Small leaks around the master cylinder will eventually dissolve away the paint on your bodywork in the general vicinity of the leak, and then give rust a chance to attack the body of your car!
*DOT4 fluid is generally about 50% more expensive than DOT3 fluid.
*Since DOT4 fluid still absorbs some water, any moisture absorbed by the fluid can encourage corrosion in the brake lines and cylinders.

DOT5
DOT5 brake fluid is also known as "silicone" brake fluid.

Advantages:
*DOT5 doesn't eat paint.
*DOT5 does not absorb water and may be useful where water absorption is a problem.
*DOT5 is compatible with all rubber formulations. (See more on this under disadvantages, below.)

Disadvantages:
*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
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.


Unless otherwise noted, your celica came with DOT 3 fluid. DOT 4 is an inexpensive upgrade. My favorite brand of DOT 4 is Valvoline SynPower because it's cheap, performs well, and is easy to find.

For DOT 5.1 fluid, I prefer ATE Superblue. Excellent performance at a decent price.

EvilSpeeder
12-09-2004, 08:38 PM
Good article!

Hooligan
12-09-2004, 08:42 PM
Is DOT5.1 mixable with DOT4 and DOT3? I would assume so since neither are synthetic.

Adrian Avgerinos
12-09-2004, 09:34 PM
Is DOT5.1 mixable with DOT4 and DOT3? I would assume so since neither are synthetic.



*DOT5.1 is said to be compatible with all rubber formulations.


In otherwords, yes, 3,4,5.1 can all be mixed together.

Hooligan
12-09-2004, 11:17 PM
Thanks. I assumed the rubber formations thing was talking about seals in the system (as it mentioned something before about incompatible parts in some cars).

skyman88
01-11-2005, 05:58 AM
Hey,
By far the best fluid I've used is Motul RBF 600, a little more expensive but worth it.

http://www.hrpworld.com/index.cfm?form_prod_id=92_138&action=product

~SKY~

Littleoldlady
01-16-2005, 04:21 PM
Beware when using 'racing' brake fluids as many are more hydroscopic than normal DOT4. Basically they absorb more moisture than normal brake fluid so need changing more often. Toyota recommend you change your normal brake fluid at least once every two years.
And yes, to meet DOT requirements all brake fluids can be mixed together without any problems although if you mix Dot 5.1 with dot 3 the fluid will not be as good as DOT 5 on its own. I would suggest flushing the system with some Methylated spirit (Dematured alcohol) first as this will clean all the old fluid out but won't damage the seals.

*You should NOT mix DOT 5 with ANY other type. It is NOT compatible.
Dot 3, 4 and I guess 5.1 are mixable.*

caneman
06-01-2005, 02:14 PM
How does one "flush" the braking system?

turbo4ag
07-23-2007, 09:58 PM
I was once told besides the ability to absorb water, the consistency itself is different in DOT4 & DOT5. Which is the equivalent of putting 20w-50 oil in an engine made for 5w-50.

Essentially destroying all the seals in the system, and possibly causing premature failure of the brake calipers. Is this true? Im just going off of what my teachers tell me in school. Who are all ASE Master technicians.

KoreanJoey
07-23-2007, 11:58 PM
no that is not the case. DOT 5 will, however, eat paint... so don't get any on your paint. I can't rememer if it is DOT 5 or DOT3/4 that's a silicon base.

*shrug*

alltracman78
07-24-2007, 01:01 AM
Dot 5 is a silicone base.
Dot 3,4 and 5.1 are a glycol base.
They are NOT interchangeable [silicone and glycol].

You flush the system by basically bleeding it.
Flush it until clean fluid comes out the bleed port.
I do it a bit longer than that.
You can buy a bleeder, or use a vacuum pump.

It takes a good gallon of fluid if you're vehicle [probably everyones here] hasn't been flushed regularly.

celicaGT90_05
07-24-2007, 02:38 AM
no that is not the case. DOT 5 will, however, eat paint... so don't get any on your paint. I can't rememer if it is DOT 5 or DOT3/4 that's a silicon base.

*shrug*

I'm just jumpin in here, but I've heard multiple times that any brake fluid eats at paint and the only thing you want to do is rush water or anything with water in it thats available over it. Using a wrag will smear paint and rub the fluid in the metal. I'd just prefer to do that for any brake fluid rather than risk it

GotToyota?
09-28-2007, 08:29 PM
Does anyone know much about Valvoline Synthetic brake fluid? I've heard it was good stuff and I bled my brake system with it. Seems really great. Anyone have any feedback about it?

http://www.valvoline.com/pages/products/product_detail.asp?product=51

-Matt

KoreanJoey
09-28-2007, 08:54 PM
Yeah I think it's DOT 4. I'm not too sure though.

smog7
02-26-2008, 07:54 AM
so changing to dot 4 from dot 3 will not lead to any ill effects?

KoreanJoey
02-26-2008, 08:02 AM
No, it'll be fine, you can also change to DOT 5.1

Not DOT 5 though.

celicaGT90_05
02-26-2008, 03:05 PM
^ yup, DOT 4 and 3 are compatible, but I prefer to use the recommended fluid. However, it wont hurt anything

Luni
02-26-2008, 11:45 PM
Not all ATE Superblue is 5.1 fluid.

I have 2 quarts of the stuff in my garage that are dot 4.

Uncrck2
06-30-2008, 08:47 PM
can i change to dot 5? im guessing i have to flush the system completly to do that

ciento44
06-30-2008, 09:10 PM
Disadvantages:
*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.


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