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Is All DOT 3 Brake Fluid the Same? #5236384 10/10/19 09:20 PM
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Gebo Offline OP
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Just found out I got one more car to change the brake fluid in. I found some unopened Nissan Super Heavy Duty DOT 3 and I may have to use it to have enough without going and buying more.

I used some Amsoil brake fluid and some ATE Type 200 in my changes over the last week. I have 2 bottles of Amsoil which says "Synthetic" and was figuring on mixing the Amsoil and the Nissan for this last brake fluid change.

Aren't all brake fluids "synthetic"? Are all DOT 3 Brake Fluids the same?


'98 LEX LS400 310K
'02 4Runner 250K
'05 Lex LS430 90K
'07 Lex GX470 75K

Shell Gas and Truck 5w-30
Amsoil OE 10w-30
Toyota ATF's and Coolant
Amsoil Gear Oil and Grease
Re: Is All DOT 3 Brake Fluid the Same? [Re: Gebo] #5236401 10/10/19 09:34 PM
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double vanos Offline
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This is just me but I wouldn’t recommend it. Had a Mazda I was flushing the brakes on. Put a non-Mazda fluid (that supposedly met specs) in the siphoned out master cylinder and had an immediate reaction, glops started forming right away. Must have reacted to the little fluid that remained in the MC after siphoning. Siphoned all that out, got some Mazda fluid and no reaction. I can’t imagine what happened but after using the Mazda fluid I finished the brake bleed with no problems.
Since that incident I’ve only used manufacturer branded fluid and had no problems.


Sabine Schmitz is the Queen of the 'Ring; Svetlana Kapanina is the Queen of the SKIES...
Re: Is All DOT 3 Brake Fluid the Same? [Re: Gebo] #5236405 10/10/19 09:40 PM
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NoNameJoe Offline
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No they are not exactly the same chemically. They are only all guaranteed to meet the DOT spec which is mostly a performance measurement/spec but probably affects some parts of the chemical makeup too (like whether it's silicone-based). Manufacturers are free to put whatever additives they want in there to meet the DOT spec or exceed it. Honda frequently claims their DOT 3 brake fluid is "heavy duty" implying they exceeded the standard for protection of seals and corrosion.

So in short, what brand you choose can matter but you can be rest assured if they meet the DOT spec you're looking for at least they meet the baseline. You will probably want something above baseline though.


2015 Civic LX Coupe
Re: Is All DOT 3 Brake Fluid the Same? [Re: Gebo] #5236407 10/10/19 09:41 PM
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Reddy45 Offline
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Yes it's all the same because it's a specification.

Re: Is All DOT 3 Brake Fluid the Same? [Re: Gebo] #5236435 10/10/19 10:14 PM
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JHZR2 Offline
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It’s hard to say, really. In theory, the bulk chemistry of a DOT 3, 4, 5, or 5.1 are roughly the same across manufacturers. They do differ between DOT spec of course... one is silicone, each has a different tenacity for water, and different boiling points.

But a few years back there was a to-do with either Honda or Toyota due to incompatibility of seals with fluids that didn’t have their additives.

I believe all brake fluids are synthesized. They aren’t refined products at least. So the use of the term synthetic is really a sales tactic.

Re: Is All DOT 3 Brake Fluid the Same? [Re: Gebo] #5236482 10/10/19 11:23 PM
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The_Cams Offline
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I mix DOT 3's all the time. Prestone, AZ, AAP, Super Tech (ST). They all work. I've stuck with ST lately since they're usually the cheapest. As long as it meets spec, works for me.

Re: Is All DOT 3 Brake Fluid the Same? [Re: Gebo] #5236502 10/11/19 12:14 AM
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JEL01 Offline
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I’ve used the Autozone brand DOT 3 in my Accord for years


Cars I maintain:
02 Mercedes CLK430
09 Honda Accord V6
13 Lexus RX350 AWD
02 Toyota Tundra 4x4
18 Lexus GX460
Re: Is All DOT 3 Brake Fluid the Same? [Re: NoNameJoe] #5236509 10/11/19 12:30 AM
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rubberchicken Offline
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Originally Posted by NoNameJoe
No they are not exactly the same chemically. They are only all guaranteed to meet the DOT spec which is mostly a performance measurement/spec but probably affects some parts of the chemical makeup too (like whether it's silicone-based). Manufacturers are free to put whatever additives they want in there to meet the DOT spec or exceed it. Honda frequently claims their DOT 3 brake fluid is "heavy duty" implying they exceeded the standard for protection of seals and corrosion.

So in short, what brand you choose can matter but you can be rest assured if they meet the DOT spec you're looking for at least they meet the baseline. You will probably want something above baseline though.


Except silicone based fluid must be labeled DOT 5, and is not compatible with DOT 3, 4 or 5.1 .

Re: Is All DOT 3 Brake Fluid the Same? [Re: Gebo] #5236556 10/11/19 04:35 AM
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demarpaint Offline
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Is all DOT 3 brake fluid Identical, is tough call. There can be slight differences from one mfg to another. Can they be mixed without issue? Yes, with no problems at all.


God Bless Our Troops

Re: Is All DOT 3 Brake Fluid the Same? [Re: Gebo] #5236561 10/11/19 04:52 AM
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Gebo Offline OP
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Thanks!


'98 LEX LS400 310K
'02 4Runner 250K
'05 Lex LS430 90K
'07 Lex GX470 75K

Shell Gas and Truck 5w-30
Amsoil OE 10w-30
Toyota ATF's and Coolant
Amsoil Gear Oil and Grease
Re: Is All DOT 3 Brake Fluid the Same? [Re: Gebo] #5236600 10/11/19 06:30 AM
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Jimzz Offline
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The Dot number is a spec, not a formula. So if it says it meets Dot3 for example that means it must have a dry boiling point of 401 °F and wet boiling point of 284 °F.
I've noticed many Dot3 either are very close to Dot4 minimum spec or even go a little over.

But as long as it meets the spec, or better, that your car calls for it will be fine. Minus Dot5 which is silicone. Yet Dot5.1 is not and can be used in Dot3 or 4 systems. Not sure what genius thought that was a good idea.


yup
Re: Is All DOT 3 Brake Fluid the Same? [Re: Gebo] #5237128 10/11/19 03:19 PM
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DOT specs are just specs and define the chemical basis for a brake fluid. But there are differences between brands. Supposedly Japanese fluid is closer to a DOT4 chemically and adds in another ingredient to help lubricate seals.

There are only a handful of brake fluid suppliers in the US/Europe/Japan. Dow, CCI, BASF and Clariant are the main suppliers. ATE, Bosch and the German OEMs and probably Castrol get their stuff from BASF and Clariant. CCI is the Japanese supplier of choice but they also have contracts with a few bottlers as well. Dow got their business from Union Carbide.

Re: Is All DOT 3 Brake Fluid the Same? [Re: Gebo] #5237192 10/11/19 04:06 PM
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DOT 3 is DOT3. Just like R-12 is R-12 and r134 is r134. Brand will vary within the spec but whether one will be noticeably better than the other is subjective.

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