what brake fluid?

[ZR8ED]

Here is a question.. what type of performance brake fluid you guys running?.. performance street Z that is...

 

dot 4? or????

 

synthetic?????

 

brand?????

 

 

its time to replace mine...

[denny411]

I personally use dot 3. I`ve heard of some people using dot 4 but it is usually required only in European cars. if you do switch to dot 4, be sure that you have all traces of dot 3 removed from the system. They are NOT compatable.

[johnc]

Motul 600.

[TimZ]

I`ve heard of some people using dot 4 but it is usually required only in European cars. if you do switch to dot 4, be sure that you have all traces of dot 3 removed from the system. They are NOT compatable.

 

I'm pretty sure that DOT 3, DOT 4 and DOT 5.1 are compatible - you won't get full performance from the higher grades if they are mixed, though.

 

DOT 5 (silicone) is not compatible with the others, and is generally a bad idea for a performance car.

 

I'm using ATE Blue (DOT 5.1), btw.

[SleeperZ]

I use DOT 4 with the highest possible dry boiling point. Wet boiling point is irrelevant because you should bleed the brakes before every event, and change the fluid annually. I've been using Valvoline synthetic with excellent results, but I hear Ford heavy duty fluid is highly recommended as well. Do not use a silicone based fluid.

[Synlubes]

I`ve used Valvoline synthetic for the past two years and have had good service from it.

I previously use Castrol.

I have heard that the Ford stuff is good also.

[Guest rick458]

What is the problem with DOT 5

[johnc]

DOT 5 is silocon based and doesn't handle the heat well. DOT 5.1 is a special type of DOT 4 brake fluid that's supposed to be realy good for racing but I've yet to see anyone run it on the track.

[JMortensen]

I agree with John C, Motul 600 or I've also used ATE Super Blue.

 

Jon

[jt1]

Both the Motul and ATE are good. I use the Valvoline Synthetic blend Dot 4 with excellent results. It's got good boiling points and it's 4.99 a quart. In the NC humidity, you need to change fluid reguarly to avoid moisture contamination. I bleed the system well before each event, hammer the brakes unmercifully at the track, and have had zero problems so far.

 

John

[Afshin]

Well here is one very long answer/summary:

 

DOT 3,4 and 5.1 fluid are all glycol based and generally compatible. However one may offset the benefit of the better fluid if mixing it with lower grade, so it’s always better to flush the whole system with the newer fluid. Also some are more different than others despite the same DOT rating, ie synthetic, different viscosities and different amount of hygroscopic (water absorbing) properties causing them to absorb brake system moisture, and over time the boiling point is gradually reduced.

 

The Dry Boiling Point is the temperature at which a brake fluid will boil when new in its non-contaminated state and the wet boiling Point is the temperature a brake fluid will boil after it has been fully saturated with moisture. The requirement for wet boiling point minimum for DOT 3 is 284F, 356F for DOT 5.1 and 311F for DOT 4. These numbers are the minimum and many of the better brands far exceed the minimum requirement (e.g. castrol SRF has wet boiling of 518F, dry boiling of 590F).

 

Difference between Dot 4 and 5.1:

DOT 5.1, albeit confusing in designation, is effectively a lighter viscosity synthetic poly glycol fluid with DOT 4 performance parameters. It was developed for use in mechanical ABS systems that require a higher cyclic rate. It is not a “higher “performing fluid.

 

DOT 5 is a silicone based synthetic fluid originally designed for use in military and government vehicles where regular maintenance could be problematic. It is non corrosive and is marketed as a “lifetime†fluid often used to preserve brake systems in antique vehicles and those that sit for long periods of time between use. It was never intended for high performance application. DOT 5 fluid is not hygroscopic, so it does not absorb water and may be useful where water absorption is a problem as one of the reason for its development (military equipment and tropical environment..). However and perhaps ironically this brings up another serious concern as moisture enters the system (can not be prevented), it is not absorbed by the fluid, and can result in moisture collecting in the calipers which can very easily boil causing vapor lock and system failure or can cause corrosion where the water collect (it has to collect somewhere since it is not absorbed). DOT 5 fluid is now most used/best suited for show car applications where its anti-corrosion and paint friendly characteristics (does nor ruin paint) are important. DOT 5 is not compatible and can not be mixed with other fluids since it can result in slugging.

I think previously some race teams used to use DOT 5 it because of it’s higher boiling point, however the new poly-glycol synthetic fluid have the same or even better boiling point along with better pedal feel (dot 5 is more compressible and has spongier pedal feel) so DOT 5 has fallen out of favor.

 

Personal recommendations:

DOT 3 is outdated and not suited for aggressively driven cars, dot 5 is problematic and should be avoided. dot 5.1 is good and best suited for ABS systems which leave us with dot 4.

I think that motul 600 is probably the best for most of us since its performance is second best (based on wet/dry boiling point of 421/585F) along with Neo (identical) but is also very well priced. Castrol SRF is the highest performing (wet/dry 518/590F) that I could find but it is also about 3 times more expensive.

Finally the best high quality and cheap fluid seems to be the Ate type 200 fluid (wet/dry of 392/536F) which is very cheap has a wet boiling point of 100F greater than for Ford HD or AP 550 fluids (AP 5.1 matches the Ate but is much more expensive). I hope this helps

 

(this info was pooled from various brake related web sites and from a nice summary by Jeff Lucius)

[Guest Anonymous]

Motul 600 is a racing brake fluid and is NOT designed to be left in vehicles for extended periods. It is for applications where the fluid is changed very frequently. It is an excellent fluid and while dry has a very high boiling temperature, but it is EXTREMELY hydroscopic....much more so than conventional brake fluids. ATE is an excellent fluid for vehicles where the fluid is only going to be changed every year or two.

[Afshin]

You bring up a very good point about the degree of hygroscopic affinity in race vs non race fluids. However, while motul 600 is clearly a racing brake fluid, it is also designed to be a street fluid. Indeed it is commonly used as such and is recommended by many aftermarket brake upgrade manufacturers for "daily use", these would include comptech and m2 performance which had it's WRX cars features in car and driver and turbo magazine. I also believe that stillen was/is using it for many of the high performance street and track kits. Furthermore its wet boiling point still exceeds the dry boiling points of many other fluids. Finally Dave Wolman one of the VP's of motul also recommeds it for certain street cars (well maintained/enthousiates cars that get reasonably frequent brake fluid flushes)

However, your point is well taken and I should consider this aspect in addition to just dry and wet boiling point in the final recommendation, so here is an addendum after doing some more research for daily vs track applications (which I should have done from the beginning).

New and improved personal recs:

Castrol SRF. amazing fluid, very low hygroscopic affinity (does not absorb much water) and the highest boiling points, and the most expensive by far (actually it is a silicon ester not a glycol based fluid, but it is not the same as the dot 5 plain silicon which can't be contaminated with glycol based fluid)

Castrol LMA. (LMA=low moisture affinity) cheap, available at most stores, not race fluid but very good as low maintenance and high performing fluid and is actually suitable for most aggressive street applications and can still handle a track or two (wet/dry boiling 325/490)

Motul 600. one of the best race fluid, can be used for daily street/track cars. Does absorb more water (more, but not extremely hygroscopic).Great choice if car goes to track often, if you don't leave fluid in over 8-12 months and if live in a dryer climate.

Ate type 200 also known as super blue and super gold. Outstanding fluid good for race and street, can last for two years (not racing off course). This fluid is possibly the best for aggressive street as well as track use type of car/driver.

One last point, while technically the different non dot 5 fluids are all compatible, it is not advisable to mix them since people have reported poor performance, spongy pedal feels and so on when doing so. It is best to flush the system when upgrading to a better and new fluid.

I just summarized my research from various brake related web sites. It would be nice now to get some personal preference from those with extensive track experience on the different fluids (since I'm clearly not one of them, at least not yet ).