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20

If the manual is saying small amounts of DOT3 can be used, what they are most likely saying is if you find yourself with low brake fluid and only DOT3 is available, it is better to use that than to not have brake fluid. Once you get back home though you need to get the recommended DOT4 back in the system by bleeding the system and filling with DOT4. As ...


14

DOT4 brake fluid has a higher boiling point than DOT3, making the fluid less likely to boil. Using cheaper, lower-grade fluid increases the chances of your brakes failing in situations where they build up lots of heat, e.g., driving down a mountain on a twisty road. More information: http://www.carbibles.com/brake_bible_pg2.html


9

Most people realize that brakes work by turning kinetic energy into heat. The brake rotors and pads get very hot, this heat is transferred to the brake fluid as well, if the brake fluid gets too hot and boils it effectively puts air in the lines and will lead to brake failure. You can put DOT 4 in place of Dot 3 but not the other way around. Note DOT 5 is ...


6

Check Brake Fluid on Wikipedia. DOT 5 is not interchangeable or compatible with DOT 3, 4, and 5.1 fluids and can cause catastrophic system failure. Dot 3, 4, and 5.1 are glycol ether based. They are compatible, but like motor oils, you should use the recommended or higher grade fluid. Dot 4 and 5.1 also have borate ester to handle higher temperatures. DOT ...


6

The main difference of DOT3 and DOT4 is boiling point of the fluid. The DOT3 standard has a lower minimum boiling point requirement then DOT4. Not all fluids are made equal and they will all typically list what both their Dry and Wet boiling points are. You can have one DOT3 fluid that just barely makes it past the standard, then another that can handle ...


5

The information & links posted by Paulster2 offer excellent explanation of what the various types of brake fluid are. There are a few grade : DOT3 DOT4 DOT5 DOT5.1 The difference between them is a specificed standard regarding the boiling temperature, which rises as the DOT number rises, and amount of water absorption. There are based on two ...


5

I found this description of synthetic based brake fluids. According to the page, all brake fluids are technically "synthetic" in that they are man made and do not contain a petroleum base. "Synthetic" brake fluid, as we think of it, has a silicon base. Non-synthetic brake fluid (normal brake fluid) is glycol based. There are trade offs to each type. Silicon ...


5

Not all sure how much of this is true but info I so far know and go by, DOT 4 has a higher boiling point and also has borate esters. DOT 5 is silicone based This is the dry boiling point minimum as I know of; DOT 3, 205 C (401 F) DOT 4, 230 C (446 F) DOT 5, 260 C (500 F) DOT 5.1, 270 C (518 F) In Australia DOT 3 is supposed to have min 230 C ...


2

DOT 5 is silicone based and is no way compatible. Dot 5.1 is sort of OK but not recommended to mix with 3 and 4. To use Dot 5, you MUST replace all rubbers, seals and flex brake lines as well as flush steel lines. How do I know ? I am running it in my muscle car.


1

A couple of things here. First, when I find the brake reservoir low, I will look at my disk brakes to ensure the pads aren't shot (or nearly worn out). Usually, if worn enough, the fluid level will drop to a point where the brake light will come on as you described (most notably so if both back and front are worn out). With that in mind, consider just ...


1

Dot 4 supercedes Dot 3. If you put Dot 4 in, no problem. Basically, Dot 4 can go in and replace Dot 3, chances are you already have Dot 3 in anyway. Wikipedia, Dot 4: While a vehicle that uses DOT 3 may also use DOT 4 or 5.1 Note: Dot 5 is not compatible with either, it is a different chemical makeup based on silcon. Putting Dot 5 in a Dot 3/4 ...



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