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Brake fluid recommendations

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Norton47

Jedi Warrior
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Would like some input on brake fluids.
The PO gave me a bottle of Castrol GT LMA and said this is the only stuff to use, all others will ruin the seals.
This is a DOT 3 and DOT 4 replacement. Will the bottle of Valvoline SYN power full synthic fluid that is a DOT 3 and DOT 4 fluid be ok. It's much easier to come by.
Thanks
 
????? I thought that synthetic fluid was all DOT5.
I could be wrong about that, but as far as I have seen, you don't want to mix mineral based (DOT 3-4) and synthetic (DOT 5) fluids. Your best bet, unless you want to completely flush and convert the system, is to source the Castrol GT LMA, or an equivilant DOT 4 fluid
 
My understanding -

DOT 5 = Silicone, which is of course synthetic.

DOT 5.1 is also synthetic (but not Silly-cone) and claims to be compatible with DOT3 & DOT4 but has a higher boiling point.
 
Well this is why I asked.
my reseach has found that glycol-based fluid are DOT 3 and 4 types, and DOT 5 is silicone-based fluid.
This Valvoline product is a glycol product according to the MSDS
Ingredient(s) CAS Number % (by weight)
-------------------------------------------- ------------- -------------
MIXED ALKYL ESTER 35.0- 45.0
TRIETHYLENE GLYCOL MONOBUTYL ETHER 143-22-6 20.0- 30.0
TETRAETHYLENE GLYCOL MONOMETHYL ETHER 23783-42-8 5.0- 15.0
POLYETHYLENE GLYCOL 25322-68-3 5.0- 15.0
TRIETHYLENE GLYCOL MONOMETHYL ETHER 112-35-6 5.0- 15.0

The MSDS for Castrol says
Mixed glycol ethers, glycol ether borate esters,
glycol derivatives, alkylamines and alkyl aromatic.
I don't think it is mineral based at all. Please see Castrol msds and Valvoline Valvoline MSDS
Although not listed as such that I can find I wonder if this Valvoline product is the new DOT 5.1.
I dunno just trying to figure it all out.
 
[ QUOTE ]
????? I thought that synthetic fluid was all DOT5.
I could be wrong about that, but as far as I have seen, you don't want to mix mineral based (DOT 3-4) and synthetic (DOT 5) fluids. Your best bet, unless you want to completely flush and convert the system, is to source the Castrol GT LMA, or an equivilant DOT 4 fluid

[/ QUOTE ]

This has been debated ad nauseum. For my $$, it's Castrol GT LMA, change it out every year or so. Cheap insurance, relatively speaking!

Mickey
 
Totally agree with Mickey. LMA stands for "Low Moisture Activity (LMA) formulation provides maximum protection against vapor lock brake failure" which is recommended for cars that are not driven every day. Also the HVDA 5-speed requires DOT3-4 not Silicone so we use it in both clutch and brake.
 
Norton, you are correct. I was mis-labeling DOT3-4 as "mineral" based. Sorry for the misinfo.
Still I also agree. stick with Castrol GT LMA. It's available through Moss, and at most Performance type parts stores. I've never heard a bad thing about it. (other than the old paint lifting thing common to all DOT 3-4 type fluids).
 
Sorry to open an old debate, I tried the search but must be doing something wrong. when I use +brake+fluid in get nothing found.
 
hehehehehe even the forum dosen't want to get into it /ubbthreads/images/graemlins/jester.gif
 
Well, there was the thread called "hydrolic fluid" back on the 7th of this month.

Oh, Castrol GT LMA is often available in the small bottles and / or quart bottles at Pep Boys. Used to be just about everywhere, even Kmart, but not as much as it used to be.
 
I use ATE Super Blue in all of my (old) cars with great results. No problems with destroying seals, absorbing water, etc
 
ATE Super Blue Racing brake fluid has a dry boiling point of over 530 degrees F, far exceeding DOT 4 standards. Mixes with any other DOT 3 or DOT 4 fluid
 
Norton:

FWIW, I have only used the Valvoline SYN power brake fluid (if that is the stuff in the tan bottle) since I have owned my '74 TR6 (15+ years). I have never had a problem with it destroying seals or leaking.

Matt
 
The potential problem with using Super Blue, or other racing type fluids is that while their "dry" boiling popint is very high, the "wet" boiling point is usually at the minimum DOT 3 level. This is because racers change their fluid every weekend so the wet boiling point is irrelevant.
When I was doing Solo events on a regular basis I used Ford Heavy Duty, a DOT 3 fluid that is cheap but has a dry boiling point of 501 degrees IIRC, but now have switched to LMA as I plan to leave the fluid in for a couple of years at a time.

Simon.
 
Simon, you are correct - the Ford DOT 3 is great for racers (an old Carroll Smith trick) and has a dry boiling point of 550 F, although lately I've heard they've reformulated it to 500 F. It is more hygroscopic (water absorbing) than regular DOT 3, so not too good for cars that sit a lot. I use it exclusively in my car as it sees lots of autocross and track time, and is completely flushed yearly.

For cars that sit, Castrol LMA is the way to go, although a yearly bleed of the brakes is still good maintenance.
 
please excuse my ignorance, but can someone explain to me the difference between dry boiling point and wet boiling point?
 
Thanks everyone
I have found that National Auto parts has Castrol GT LMA by the quart and now I can decide what to use.
FWIW web search shows the DOT 3 and 4 specification for Dry ERBP is 205/401 degrees C/F and Wet ERBP is 155/311 C/F.
Castrol spec only gives one value for ERBP of 265/509 C/F. based on the value I would say this is a dry value.
The Valvoline product is rated at Dry ERBP 262/503 and wet ERBP of 173/343
Good explanation of terms and reasons is at What is ERBP

FWIW /ubbthreads/images/graemlins/cool.gif
 
FTWRWTK
For those who really want to know /ubbthreads/images/graemlins/crazyeyes.gif
See the attachment file.
 

Attachments

  • 265378-Brakefluidstory.pdf
    57.4 KB · Views: 243
The Spitfire had the Dot four put in it about three months ago. We ordered the replacement seals for the master cylinder today. On the other hand in May of 2005 The lines running to the rear of my Austin Healey had to be replaced. I used the Valvoline SYN power full synthic fluid that in fact says full synthetic exceeds Dot3 and Dot4. I replaced the lines and bled them using the Valvoline. They have required nothing but topping off the Cylinders when I do maintenace. I have put twenty seven thousand miles on it and have not had to bleed the brakes or the clutch. When the kit arrives for the Spifire master cylinder I plan to use the Valvoline.

Anthony
 
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