Differences in Brands of Dot 4 question

Messages
676
Location
TX south plains
For the brake work I'm about to do on my 1994 Jag XJS I'm looking at the fluid. Dot 4 is required and I've read on the Jag forum that the highest boil point you can get is recommended. It's a very heavy car with a good pulling engine. I got Break Best dot 4 with a 475 degree boiling point since it was the only dot 4 at the O'reilly I like to shop at. I can get Valvoline synthetic dot 3/4 at Advance down the road with a 480 boiling point. I can get Amsoil online for a lot more than either of these but it has a 580 degree boiling point. So, is there much difference in the real world between any of these? Is the amsoil really worth double (and for a smaller bottle)? Is there another brand I should look for?
 
Messages
5,091
Location
USA
Brake fluids are mostly all the same.They have to meet minimum standards 3/4/5,to comply with the DOT specs.Most any brand is ok,however,the el cheapo brands (dollar or so)have been caught in the past not meeting standards,and have had some recalls.I personally would stick with Valvoline,Prestone...the name brands.Cant go wrong at least with a very well known name.Unlike SNAP brand and some of the other lo line names.
 

JHZR2

Staff member
Messages
46,257
Location
New Jersey
I think all brake fluid is "synthetic". Someplace I read that the higher the boiling point of DOT4, the more succeptible it is to moiusture absorption... of course the wet BP is lower, so it may create a moot point. If youre getting the fluid hot enough that 5C is an issue, you have problems. I'd use what is readily available at a decent price in a name-brand, sealed package.
 
Messages
8,859
Location
Texas
DOT 5 carries its own risks: water pooling in low points in the brake system since it doesn't mix with the fluid, lower lubricity for things like ABS pumps, etc. Be careful considering DOT 5 instead of DOT 4.
 
Messages
1,154
Location
Richmond, VA
DOT5 is also compressible (scary mushy pedal). Go with the dot4 if your car is spec'd for it. Reasons being: seal compatibility, non-compressible, proper viscosity, and peace of mind. If you're boiling brake fluid you'd already be going for the Amsoil or an ATE product anyway.
 
Messages
5,153
Location
MW
I use Valvoline DOT 4 fluid in our BMW and Audi. No problems so far. The factors that affected my choice of the brand: - it's DOT 4 from a reputable company; - Valvoline is the only brand name available in retail stores wherever I have looked.
 
Messages
19,479
Location
Chicago Area
I use anybody's DOT 4. If it meets the spec, why not? Those temps are really high, anyway. it is above the igniting/burning point of paper. Racers and movie type stunt driving may need higher boiling points. But for the street for 99.99% of us, it will never be a problem.
 

cadfaeltex

Thread starter
Messages
676
Location
TX south plains
Originally Posted By: mechtech2
I use anybody's DOT 4. If it meets the spec, why not? Those temps are really high, anyway. it is above the igniting/burning point of paper. Racers and movie type stunt driving may need higher boiling points. But for the street for 99.99% of us, it will never be a problem.
Thanks for all the input everybody. mechtech, this is what I was thinking when I looked at the price of the Amsoil.
 
Messages
13,616
Location
Frisco, TX
Short of track events (20+ minute periods of heavy braking and WOT), any off-the-shelf DOT 4 fluid will be sufficient. I run Motul RBF 660 but that's because I have a 4000lb car that gets to 120+ on the track and needs to stop safely.
 

cadfaeltex

Thread starter
Messages
676
Location
TX south plains
Originally Posted By: dparm
Short of track events (20+ minute periods of heavy braking and WOT), any off-the-shelf DOT 4 fluid will be sufficient. I run Motul RBF 660 but that's because I have a 4000lb car that gets to 120+ on the track and needs to stop safely.
Hmmm, 20+ minutes of heavy braking and WOT - sounds like when I used to commute across Houston (with the emphasis on the more than 20 minutes)
 
Messages
6,388
Location
Washington St.
DOT4+ or DOT5.1 is the upgrade to DOT4. 4+ and 5.1 are NOT silicone and are completely suitable and compatible in any system calling for DOT4. Get the brake fluid with the highest WET boiling point. That one will give you the most protection in the future after the fluid has absorbed some moisture but before it is again due for a change. ATE (say ah-TAY) DOT5.1 brake fluid is among the best with a wet boiling point of 392°F. The minimum for the DOT4 spec is 311°F, so it is easy to see that just meeting spec isn't the safest you can get. ATE is available with either the natural amber color or dyed blue to make it easier to tell when you've flushed enough at a brake fluid change. http://www.raceshopper.com/ate_brake_fluid.shtml
 
Messages
903
Location
wa state
I have been using ATE Superblue for a few years now. I hit the roadcourse every now and then, no problems at the track or daily driving. its $12-$16 for 1L depending where you can find it. I found a local performance shop that builds Volvos for roadracing that sells it. Most people order it online Features/Benefits of ATE Super Blue Racing Brake Fluid: •Blue tint of fluid makes bleeding brakes easier •Ideal for race use, excellent choice for street driven vehicles, too •Boiling point minimum: 536 degrees F •Wet boiling point minimum: 388 degrees F •Viscosity at -104 degrees F: max 1,400 mm 2/5 •Designed to last up to 3 years under normal highway driving conditions
 
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cadfaeltex

Thread starter
Messages
676
Location
TX south plains
I like the idea of the super blue as much for the color as anything. Would definitely make it easier for me to tell when I've got all the old stuff out. The old stuff doesn't look too dark but it looks strangely inconsistent. I'm sure when the replaced the master cylinder at the dealership before I bought it they used the cheapest of everything they could get. Brakes don't feel bad but I imagine they should feel better.
 
Messages
9,614
Location
Pennsylbammyvania
Originally Posted By: dparm
Short of track events (20+ minute periods of heavy braking and WOT), any off-the-shelf DOT 4 fluid will be sufficient. I run Motul RBF 660 but that's because I have a 4000lb car that gets to 120+ on the track and needs to stop safely.
The 660 has a lower wet boiling point than the RBF600 (by at least 22*F), so if he is going to use one of these for the street he should go with the 600. (I have NO clue as to the rates/speed of moisture absorbtion differences between these 2 Motul fluids. ??? ) Of course, you either bleed, or completely flush out your system often, due to open tracking, so you benefit more from the 23*F or so higher dry boiling point of the 660.
 
Messages
13,616
Location
Frisco, TX
Originally Posted By: dailydriver
Originally Posted By: dparm
Short of track events (20+ minute periods of heavy braking and WOT), any off-the-shelf DOT 4 fluid will be sufficient. I run Motul RBF 660 but that's because I have a 4000lb car that gets to 120+ on the track and needs to stop safely.
The 660 has a lower wet boiling point than the RBF600 (by at least 22*F), so if he is going to use one of these for the street he should go with the 600. (I have NO clue as to the rates/speed of moisture absorbtion differences between these 2 Motul fluids. ??? ) Of course, you either bleed, or completely flush out your system often, due to open tracking, so you benefit more from the 23*F or so higher dry boiling point of the 660.
Sorry, should've made that distinction. My point was merely that racing fluids in street cars is not necessary.
 
Messages
19,686
Location
Sunny Florida
I have tracked my 4000 pound whale all over the country on regular DOT 4 fluid. The brakes are factory 4 piston fixed calipers against 14 inch rotors, and I ran well over 150 mph at Homestead coming around to the infield raceway entrance. Never a peep. You might WANT racing fluids, and the silicone based can help with special issues, but it is likely not needed.
 
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