DOT-3 vs DOT-5 vs RBF-600????

[Xrossfader]

So I'm about to flush my system, replace my lines and rotors and pads... I was going to get 'better' brake fluid but I just don't know anything about it. Buy dot-3 is all I know. So I was looking at Extreme PSI for parts and they some blue brake fluid and Motul and this 5.1 stuff... If anyone has any simple knowledge to pass along about what to pick here, I'd love to hear! Thanks in advance!

https://www.extremepsi.com/store/home.php?cat=783

Cheers,
Lukasz

 

[JusMX141]

If you're flushing the entire system, Dot 5 is by far the best way to go. Silicone has better lubricity for master cylinders and caliper pistons, doesn't draw moisture at all (it actually repels moisture), and has a ridiculously-high boiling point in comparison to most alcohol-based Dot 3 & 4 fluids. The bi*** of it is the changeover....but once it's in there you won't be disappointed.

We sell it at my workplace to classic car guys all the time- it's great for cars that sit a long time because of the fact that it doesn't draw moisture so parts like wheel cylinders and calipers last forever. It's about $17/qt versus $5 for Dot 3, but it's well worth it.


If you would've asked 10 years ago I would've speculated that by 2013 all new cars would have Dot 5 silicone brake fluid and copper/nickel brake lines for a safe braking system that would last about forever, but for some reason the manufacturers are more caught-up in every new car brand having it's own $30-per-gallon type of coolant than our safety.

 

[Xrossfader]

If you're flushing the entire system, Dot 5 is by far the best way to go. Silicone has better lubricity for master cylinders and caliper pistons, doesn't draw moisture at all (it actually repels moisture), and has a ridiculously-high boiling point in comparison to most alcohol-based Dot 3 & 4 fluids. The bi*** of it is the changeover....but once it's in there you won't be disappointed.

We sell it at my workplace to classic car guys all the time- it's great for cars that sit a long time because of the fact that it doesn't draw moisture so parts like wheel cylinders and calipers last forever. It's about $17/qt versus $5 for Dot 3, but it's well worth it.

If you would've asked 10 years ago I would've speculated that by 2013 all new cars would have Dot 5 silicone brake fluid and copper/nickel brake lines for a safe braking system that would last about forever, but for some reason the manufacturers are more caught-up in every new car brand having it's own $30-per-gallon type of coolant than our safety.

Thank you!! So that Dot 5 is the way to go. What about dot 5.1? It's in that link...

Well... the internet prevails. I hope.

What's so good about 5.1?

DOT 5.1 has a wet boiling point of 365 degrees. Better yet, DOT 5.1 is half as viscous as DOT 4. This means a system filled with DOT 5.1 provides quicker lever response, better modulation and faster pad retraction When servicing, the lower viscosity facilitates bleeding and pad adjustment. DOT 5.1 also experiences less volume change as a result of temperature shift than DOT 4, allowing more consistent braking through a range of temperature. It may require a little more effort to purchase DOT 5.1, but we feel it is well worth it. In every case make sure any fluid used is labeled 'DOT 3', 'DOT 4', 'DOT 5.1' or 'Compatible with DOT 4'.

______________________

DOT 5 is one of several designations of automotive brake fluid, denoting a particular mixture of chemicals imparting specified ranges of boiling point.

DOT 5 is a silicone-based brake fluid. It is NOT compatible with any polyethylene glycol based fluids. Mixing DOT 5 with other types of brake fluids will start a chemical reaction that will cause solids to precipitate out of the mixture and inhibit proper brake system function.

Unlike polyethylene glycol based fluids, it is not hygroscopic, however this means that instead of being dissolved, any water in the system will eventually find its way to the lowest point in the brake line, corroding it, and potentially boiling and causing brake failure. Since it does not attract moisture, there is no way this will occur unless you are careless in cleaning out of the old fluid. Its major advantage over other forms of brake fluid is silicone will exhibit a more stable viscosity index in extreme temperatures, which is why the US Army likes silicone fluids. It is widely used in the antique automobile arena as well as it will not damage paint. From a lubrication standpoint, there is no appreciable difference.

Check with the manufacturer of your vehicle to see if this voids your warranty

If you do decide to make this switch, be careful. You will have to completely flush you entire brake system of the DOT 3/4 before filling with DOT 5. Flushing with mineral spirits is enough to cause a complete system failure in a short time. In fact the introduction of any petroleum based products such as motor oil, power steering fluid, mineral oil (baby oil) even in small quantities will cause failure. The only way to properly flush this is with a brake cleaner that does not leave a residue.

In order to flush the system properly, every component must be removed and cleaned individually, then lubricated with the new DOT 5 and reassembled. You will also need to check with the manufacturer of your vehicle to see if this voids your warranty. This is the perfect time to see if any parts are worn and replace them accordingly. If done properly and no moisture is introduced into the system, you will not have to replace the internal components of your system again.

 

[JusMX141]

5.1 sounds like a synthetic version of Dot 3 or 4 with a lower viscosity for better performance in cars with ABS. I still think you're better-off with Dot 5 Silicone, although you'd have to carry some with you in the event of a problem as it's availability is not close to that of Dot 3 or 4.

 

[Xrossfader]

5.1 sounds like a synthetic version of Dot 3 or 4 with a lower viscosity for better performance in cars with ABS. I still think you're better-off with Dot 5 Silicone, although you'd have to carry some with you in the event of a problem as it's availability is not close to that of Dot 3 or 4.

Dot 5 sounds amazing. It really does but I don't think it's going to be worth it since the car will not be hitting the track at the moment. Once I upgrade the brake system I'll go with the DOT 5! Thank you for the help! I appreciate it!

 

[taz4432]

Dot 5 sounds amazing. It really does but I don't think it's going to be worth it since the car will not be hitting the track at the moment. Once I upgrade the brake system I'll go with the DOT 5! Thank you for the help! I appreciate it!

Switching over to DOT5 on a braking system that has non-silicone brake fluid in it already is a huge pain. You have to very thoroughly flush the system out to remove ALL traces off the DOT3/4/etc. brake fluid. That's why if you're going to to go to DOT5, it's easiest when you're already replacing everything.

 

[JusMX141]

^ Right. Going to Dot 5 isn't something you'll do eventually- it's now or never while the system is flushed and clean.

 

[dsmpat95]

You can use DOT 5.1 without cleaning the system from DOT 3 or 4. But you can not mix DOT 5 with none or the other fluids.

 

[Xrossfader]

Once again thanks! Since I'm not replacing the master or calipers I am going to refrain from the dot 5. Though I will when I do replace and go into a big break system.

 

[FIBA M - EC17PSE]

Thought I would just chime in, I am also soon to change my lines and fluid and as you posted in the thread title I will be going with the rbf-600 or 650 as its dot 4 based but its for more racing use and fast street, I think its a great fluid

 

[SexyDSM95]

^ I hear/read great things not only about the Motul RBF600, but Super Blue Racing as well.

 

[TSiAWD666]

If this is for a street car just buy some off the shelf dot 3 or 4 and be done. This talk about "upgrading your fluid" is moot unless you're actually putting some heat for extended periods into your brakes.

If you actually do some auto-x or track drive your car, I would be comfortable in recommending RBF600 or 660 based on my personal successful experiences with both on actual race tracks (not a common thing on this forum sadly). I've even used the 5.1, but its specs are less and I have boiled it. I don't like Super Blue personally because I was able to boil it sooner than I ever expected, sooner even than the Ford racing brake fluid you used to be able to get dirt cheap from the Ford parts counter. What fluid is enough really depends on your particular car due to brake differences, weight differences, and speed differences, so take this all with a grain of salt.

This talk of DOT 5 is really nonsense... totally not worth it on your street car.

 

[Xrossfader]

If this is for a street car just buy some off the shelf dot 3 or 4 and be done.

This talk of DOT 5 is really nonsense... totally not worth it on your street car.

I like where your heads at. =)

 

[JUANPSI]

Dot 5 is not ment for high performance use. It's for vehicles that sit like classic cars and harleys.
It's also safe for paint.

 

[Xrossfader]

Dot 5 is not ment for high performance use. It's for vehicles that sit like classic cars and harleys.
It's also safe for paint.

Oh cool! Thanks for the information!