When did an auto inspection station ever look at fluids? Even if they did the drop out or foriegn citizen would not know what is or isn't old, contaminated or incorrect fluid. Just like the TSA - they have never stopped a terrorist event or caught one. Just a waste of money anid expensive attempt to make travellers think they are safe.

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When did an auto inspection station ever look at fluids?

Perhaps inspection stations don't as it may not be required, but lots of full service stations do look at brake fluid, levels and recommend full fluid replacement every X number of years. The Florida list of approved brake fluids is not inspection related, perhaps because Florida does not have a vehicle inspection.

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Originally posted by Moonbeam-Express:


Blue brake fluid is claimed to be much harder to see a change in, whether true or not that is the theory that prevails.

Yeah. I wouldn't say it is MUCH harder, but it is not as obvious to the untrained eye. Of course, one can hope that whoever works on brakes should know what they are doing.

BTW, while on the subject of ATE, it comes in a metal can, so it does not absorb moisture on the shelf. I buy each color by the liter can. When it is partially used, I drop in marbles until the level is overflowing and replace the cap. That displaces the air to prevent moisture contamination and oxidation.

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BTW, while on the subject of ATE, it comes in a metal can, so it does not absorb moisture on the shelf. I buy each color by the liter can. When it is partially used, I drop in marbles until the level is overflowing and replace the cap. That displaces the air to prevent moisture contamination and oxidation.

Ingenious!

On my motorcycles I've always tried to replace with a different color just so I can see when the old stuff is through the system.

I haven't seen/been in a full service gas station in 35 years. Did not know that any still existed. Closest i have come is in Oregon where they do not let you pump your own fuel,......but they do not check or do anything else. You have to ask them to wash your windshield.

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Originally posted by bill h:

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Originally posted by Carl Feren:
I use a prestone syntetic brake fluid which was changed about 20 months ago.

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Not a very high wet boiling point.

This is the Brake Fluid that I use "Prestone Synthetic BF DOT 3 470○F Dry Boiling Point" I thought that 470oF was a decent boiling point compared to some others I looked at.

What is the difference between WET and DRY boiling points?

Also ... I went to the tirerack.com link posted by BONES and noticed that the ATE Super Blue is DOT 4. All the brake literature I have says DO NOT USE DOT 4 citing possible failure of seals and emphatically states to use only DOT 3 fluid.

Not being very familiar with DOT 3 vs, DOT 4 can someone please help me out with this.

Also ... back to my original thread regarding sticking brakes. (1) The brake actuator APPEARS to be OK but how do I test it? (2) Before we left Malabar on Sunday I sprayed the caliper sliders on both rear brakes with a penetrating silicone spray, pumped the brakes and sprayed some more. I noticed that on this leg of the trip my cruising speed was higher at the same RPM's and that there appeared to be considerably less drag so I can only conclude that the caliper sliders were not retracting fully and that sticky caliper slides were the problem.

Carl,

One way is to jack your tires off the ground and spin them while actuating the brakes. This will tell you if they are sticking cold.

Another way is to go run it up to temp and then do the above. Or, feel (measure) the heat from each wheel.

In lighter weight vehicles I have found a dirt road and done different hard braking efforts and then read the skid marks.

I almost always walk around my RV and trailer checking with my hand at each fuel fillup to see if there is any sign of excessive heat. After all, the brakes are a mechanical device designed to convert inertia into heat.

This following may better explain the DOT ratings and Dry Wet testing. It is tempting to always think a higher rating number is better, but you brake designer may have good reason to insist of just one due to chemical compatibility with the innards.

Department of Transportation Requirements
1. DOT 3 brake fluids meet the minimal requirements set forth by the Department of Transportation. DOT 4 fluids endure tests that are more rigorous and are used in high temperature performance vehicles.
Chemical Formulation Differences
2. All brake fluids begin as ethylene glycol or antifreeze. DOT 3 fluids, for regular vehicles, are made from polyalkylene glycol ether and other hydroscopic glycol chemicals. DOT 4 fluids have borate esters added which raise the temperature of the boiling point for better performance under extreme racing conditions.
Dry Boiling Point
3. Boiling points are the major differences between formulas. As brake fluid heats up because of friction, it boils, forming gas bubbles that lead to soft brake pedals. Dry boiling refers to new, unexposed brake fluid. DOT 3 brake fluid has a dry boiling point of 401 degrees while DOT 4 boils at 446 degrees.
Wet Boiling Point
4. Wet boiling refers to old brake fluid or fluid that has been exposed to moisture from the environment. DOT 3 boils at 284 degrees while Dot 4 boils at 311 degrees.
Water Tolerance
5. As brake fluid sits in the line, it collects moisture, which evaporates to steam, interferes with braking capabilities, reduces the boiling temperature and leads to corrosion. DOT 4 is designed to tolerate water levels better than DOT 3. Regardless of the type of brake fluid, water levels should be less than 3 percent of the total fluid in the line. For this reason, brake fluid should be changed often to reduce the amount of moisture in the line.

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Originally posted by Moonbeam-Express:
One way is to jack your tires off the ground and spin them while actuating the brakes. This will tell you if they are sticking cold.

Another way is to go run it up to temp and then do the above. Or, feel (measure) the heat from each wheel.I almost always walk around my RV and trailer checking with my hand at each fuel fillup to see if there is any sign of excessive heat. After all, the brakes are a mechanical device designed to convert inertia into heat.

I'll try that.

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It is tempting to always think a higher rating number is better, ...

I think that I will stick with DOT3 and change fluid more frequently.

Thanks for the feedback Moonbeam Express.

Carl Feren