Best Brake Fluid

[kr_bitog]

Originally Posted By: Test_Drive
Slightly OT:
Long ago, I thought about switching to Motul DOT 5.1 brake fluid. It was not because I needed the high boiling points, but because DOT 3 had a low temp viscosity limit of 1300cP, whereas DOT 5.1 was 820cP.

It became an issue during a -35*C cold snap, where the clutch was VERY sluggish due to the viscosity of the brake fluid. And of course, ABS was disabled for the first few minutes of driving during that week.

....never got around to changing it out though.

Can anybody comment on whether the difference in 820 vs 1300cP would have quelled my irritation with the molasses in the clutch?

I believe it will help.
I guess the reason why they put DOT 5.1 standard is because they want lighter viscosity for ABS working properly and high boiling point like DOT 4.

The brake fluid manufacturer normally do not advise people changing from DOT 3 to DOT 4 fluid if the system has ABS. However they recommend DOT 5.1 for compatibility with DOT 3 and DOT 4.

 

[tdi-rick]

Originally Posted By: Thingfish
The BEST?
Castrol SRF.



have to agree, although a touch over the top for the average road going vehicle

I use Castrol Response Super Dot 4 which meets Dot 3,4 and 5.1 and was developed for Porsche and BMW ABS systems.

 

[Thingfish]

Originally Posted By: tdi-rick
Originally Posted By: Thingfish
The BEST?
Castrol SRF.



have to agree, although a touch over the top for the average road going vehicle

Especially in Vegas ( or any other super dry location ) where the average humidity year round is about 12-15%.

 

[gtx510]

How about GS610?
http://www.gs610.com/GS610_Product_Specifications.html

 

[Allan_G]

I tend to stock up when I see it on sale. I have alot of plow trucks, 4wd trucks and living in Northwestern PA, do alot of rust repairs. So I go through alot of brake fluid. I try to stock up at places like AAP, or similiar. Last year I got 99C pints BOGO so for.99 I got a quart. Needless to say It was Wearever brand and I bought 36 bottles, all they had left. I guess if it meets specs, you like the name and its a known name/supplier whats the harm.

 

[Carmudgeon]

Originally Posted By: BoostinZX
So he ordered some from a distributor that we found here locally and they sent it in Quarts, but now it says "New Formula" on the front, and it says synthetic...the old bottles didn't say this...


It's funny, just as Valvoline has chosen to make their new fluid a strictly conformist DOT 3/4 fluid, Castrol has improved LMA to exceed standards, with a new wet boiling point almost equivalent to the old Synpower (343). Castrol hasn't updated their datasheet yet, but it's somewhere in the 32x-33x range. For a readily-available OTC fluid, it would appear to be the new choice.

I also came across another option, Wagner Severe Duty, which is a 5.1 non-silicone fluid that can be mixed with 3/4. It boasts 500+/356 boiling points.

Still, my favorite is Ate Typ 200. 536/392, ABS-compatible, 3 year service life, and liter.

 

[ewetho]

Motorcraft Dot 3 has a min dry boiling point of 500F

BG is nice too.

Woould not hesitate to use Castrol GT/LMA or Valvoline Synpower either.

 

[Big Jim]

But Ford's Motorcraft DOT 3 has a lousy wet boiling point. That is why they qualify it as DOT 3. I'm not a fan unless you change it often. Very often.

 

[The Critic]

Originally Posted By: Big Jim
But Ford's Motorcraft DOT 3 has a lousy wet boiling point. That is why they qualify it as DOT 3. I'm not a fan unless you change it often. Very often.


You should consider this as well:

Quote:
Ford does not recommend changing DOT 3 fluid or flushing the system. Ford says their recommendation is a "risk versus benefit" assessment because there's a potential for doing more damage than good. If sediment or contamination from the master cylinder is pushed through the ABS unit, it can cause big problems. Flushing the system also increases the risk of air entrapment and leaks, says Ford.

Ford says their brake systems are engineered to tolerate brake fluid contamination of up to 3 percent moisture without fluid boil (which is close to the saturation point for DOT 3 brake fluid). If the fluid has more moisture, it probably has some liquid water in it and should be changed.

Ford said they measured the water content in 7 to 10 year old Ford vehicles and found that the water content was actually quite low: only 1 to 1-1/2 percent. So based on their findings and the design target of 3 percent water, they see no need to change the fluid for preventive maintenance.

Does pushing the caliper pistons in when changing the pads push contaminants from the calipers back toward the ABS unit or master cylinder? Ford says no. There's not enough movement or migration to cause a problem.


http://www.aa1car.com/library/procut3b.htm

 

[cordeen]

Prestone just went from $3.94 to $4.94 in my local Walmart.

 

[dk1604]

I was trying to locate an article I read a few years ago that stated the rational for changing brake fluid wasn't moisture content but really to replenish the corrosion inhibitors. Couldn't find it but found this instead which says basically the same thing: Industry Adopts Brake Fluid Replacement Guidelines

For more fun reading, this fellow went as far as doing a cost benefit analysis of different brake fluids: Brake Fluid Comparison

 

[Big Jim]

Originally Posted By: The Critic
Originally Posted By: Big Jim
But Ford's Motorcraft DOT 3 has a lousy wet boiling point. That is why they qualify it as DOT 3. I'm not a fan unless you change it often. Very often.


You should consider this as well:

Quote:
Ford does not recommend changing DOT 3 fluid or flushing the system. Ford says their recommendation is a "risk versus benefit" assessment because there's a potential for doing more damage than good. If sediment or contamination from the master cylinder is pushed through the ABS unit, it can cause big problems. Flushing the system also increases the risk of air entrapment and leaks, says Ford.

Ford says their brake systems are engineered to tolerate brake fluid contamination of up to 3 percent moisture without fluid boil (which is close to the saturation point for DOT 3 brake fluid). If the fluid has more moisture, it probably has some liquid water in it and should be changed.

Ford said they measured the water content in 7 to 10 year old Ford vehicles and found that the water content was actually quite low: only 1 to 1-1/2 percent. So based on their findings and the design target of 3 percent water, they see no need to change the fluid for preventive maintenance.

Does pushing the caliper pistons in when changing the pads push contaminants from the calipers back toward the ABS unit or master cylinder? Ford says no. There's not enough movement or migration to cause a problem.


http://www.aa1car.com/library/procut3b.htm


I don't know where they found their sample cars. My experience is that many cars suffer from problems of contaminated/aged brake fluid anytime after about six years of age. I wish I had taken pictures of some of the Fords I have worked on with slugged up wheel cylinders and calipers. Nasty sludge.

If a master cylinder is full when the caliper piston is pushed back a large quantity of brake fluid is pushed out of the cap and all over the engine compartment and floor. If that isn't enough migration to allow junk from the calipers to get into the ABS unit, I don't know what will. It is enough to sometimes cause the cups in the master cylinder to collapse necessitating master cylinder repair to be added to the brake work.

 

[artificialist]

The other flaw in Ford's writing is that they didn't talk about the humidity outside. Here in Florida, it is a huge preoblem for brake fluid.

I never saw an ABS module fail because of a brake flush either.

While I rarely see it boil over, I do see it severely corrode the insides of brake plumbing.

That is why I switch to a good DOT 4 very quickly in a new car.

 

[The Critic]

Originally Posted By: artificialist
The other flaw in Ford's writing is that they didn't talk about the humidity outside. Here in Florida, it is a huge preoblem for brake fluid.

I never saw an ABS module fail because of a brake flush either.

While I rarely see it boil over, I do see it severely corrode the insides of brake plumbing.

That is why I switch to a good DOT 4 very quickly in a new car.


They have said that sealing materials have improved over the years, and there should be less chance of moisture contamination from the environment.

Either way, they have said that tests conclude that after ten years, the amount of moisture present is still below the design target--and that is the most important part.

DOT4 absorbs moisture more quickly than DOT3, so unless you are changing it frequently, it isn't a good idea.

 

[artificialist]

DOT 4 has been said to absorb moisture more quickly, but my experience with Ever Wear test strips indicates that it doesn't.

DOT 3 tends to be made with cheap chemicals, whereas DOT 4 gets expensive chemicals so manufacturers can call it a premium product.

 

[Tempest]

Quote:
DOT4 absorbs moisture more quickly than DOT3, so unless you are changing it frequently, it isn't a good idea.

The question becomes: Does the "absorbed" (can't be the correct technical term) water pose a hazard to parts? Or does it just sit there happy to hang around with brake fluid?

 

[cos]

cordeen,

What size bottle of Prestone DOT4 are you referring to?

 

[artificialist]

The water accelerates corrosion of steel parts.

 

[cos]

dk1604,

Thanks for the link - good info!

 

[swalve]

I remember doing this same research a few years ago, and what I found was a brand name in a bronze colored bottle. It was DOT4 and exceeded the other brands' specs. And was available at either Pep Boys or Autozone. But now I can't remember what it was called, and I don't see it on any of the MFRs websites. Otherwise, I use the ATE blue because it's cool looking.

I think that "never bleed" recommendation of Ford's is bad advice. Yeah, the system will probably function as intended for a long while. At least until the brake lines rust through from the outside. After all, most of the cars on the road have never had their brake fluid changed/flushed. But if Ford can get the fluid installed correctly at the factory, an end-user can get it done right too. Just a matter of doing it right- what Ford should have done is publish the right way to do it, and then say they aren't responsible if you screw something up doing it wrong.

And let's be logical about this- if the brake system were REALLY perfectly sealed, then the brake fluid would remain the same color as it was from day one. Right? I mean, if it's sealed, there's nothing getting in to contaminate it. But anyone who has bled brakes knows that stuff gets gross pretty quickly. I had a car that was probably 11 years old (a 91 Shadow that I was working on in like 01 or 02) that actually had a chunk of rust trapped between the master cylinder and the distribution block. Depending on the time of day and the phase of the moon, the car would either pull during braking, or the pads on that side wouldn't release and overheat the brakes. After a marathon session of bleeding and flushing, I tore apart the system and sitting there in one of the holes was the chunk. I dug it out with a pick and rebled. Tons more crarp came out and then the system worked fine.