2 Year Brake Fluid Changes--Overkill?

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nthach said:
I’ve heard mixed feelings about this - DOT4 seems to be more immune to being hygroscopic, the better fluids are formulated with borate esters on top of their glycol esters/glycol ether base chemistry. ATE/Conti, Bosch don’t make their fluid - they buy it from the two German chemical companies, BASF and Clariant. DowDuPont and CCI supply a majority of American and Asian service fill and retail brake fluid.

Japanese DOT 3 fluid tends to share the high dry boiling point as DOT4 fluid and the corrosion resistance of such. A long time ago, Toyota had a brochure at their parts counters - it states “original” Toyota fluid is based on borate ester chemistry. And there was a recall/TSB recommending only Toyota-bottle fluid in some models due to a squeal from the MC.
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Does this mean I'm good to buy Super Tech DOT4 and use it in my vehicles that spec DOT4 and DOT3?

It seems to be the cheapest per quart among all retail brands.
 
The main difference between all DOT 3 and DOT 4 fluids is the addition of borates to raise the wet and dry boiling points. DOT 3 and 4 are compatible and you can mix them safely.
 
ripcord said:
The main difference between all DOT 3 and DOT 4 fluids is the addition of borates to raise the wet and dry boiling points. DOT 3 and 4 are compatible and you can mix them safely.
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AutoZone sells a quart of Valvoline DOT4 for around $12

WM sells a quart of SuperTech DOT4 for around $6

The extra $6 for Valvoline is literally just buying a brand name?
 
ripcord said:
The main difference between all DOT 3 and DOT 4 fluids is the addition of borates to raise the wet and dry boiling points. DOT 3 and 4 are compatible and you can mix them safely.
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Reddy45 said:
Does this mean I'm good to buy Super Tech DOT4 and use it in my vehicles that spec DOT4 and DOT3?

It seems to be the cheapest per quart among all retail brands.
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It’s not my first choice of SuperTech but all brake fluids sold in the US must comply with DOT standards as prescribed. And unless you need low viscosity fluid, ST works just fine.

AMECA even “certifies” brake fluid - but the DOT FMVSS specs for brake fluid are pretty strict. Mineral oil systems such as that used in some Crewe-built Rolls-Royce and Bentley models as well as some Jaguars use HSMO which again carries the same warnings as brake fluid.
 
meep said:
So... right that would make sense. it shouldn’t compress, yet tried 3 times on 3 vehicles it was the same, and it was verified going back to dot 3. You’d think if it were placebo, I would have preferred dot 4 because of the boiling point (I did overheat and boil the fluid a few times on the 1990 Subaru loyale wagon, so I wanted dot 4 to be great.) I think I stayed with dot 4 anyway on it, but reverted later with the 97 legacy, and with the s10.

let me ask this... as the pedal is first depressed, some fluid escapes back into the reservoir until the piston completely closes off the fill hole. Could it be that dot 4 is thinner and more is able to squeak out through that orifice? With less fluid in the system, the pedal would sink further.

the first time, I thought I left air in the system and bled it again. I thought placebo as well. But not after 2 times, and certainly considering that I bled a lot of brakes and just didn’t have any kind of hiccups with that.

Lemme see if I can find the post where Critic noticed it too.
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You're not alone, another person described something similar here:

https://acurazine.com/forums/1g-rdx...3-brake-fluid-comparison-873329/#post14160310
 
I would do what the manual says even if lots of people don’t change their brake fluid and think their proof it’s overkill.

Honda says 3 years ( Dot 3 ) but I use Dot 4 and change it every 2 years. If you live in the rust belt, pay particular attention to the underside and inspect the brake lines for corrosion.

About 3 years ago, my wife got rear ended by a car that had brake lines that failed ( lucky it was slow city driving ). Driver said his brake pedal went to the floor ( why he never tried his hand brake, I don’t know ) and later brake fluid was all over the road. My wife talked to him later and he admitted his lines were rusted out and complained how expensive the repair was going to be. He did apologize to my wide though.

No mandatory annual inspections were we live and there should be unless you can prove your following the manufacturers maintenance schedule and have records to prove it.
 
Jetronic said:
Amazingly Hyundai says 2 years in Europe...

I found the low viscosity fluid helps also at regular temperatures, if you have an fast cycling ESP unit. To the point you can't feel ABS in your brake pedal.
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Bcs. In Europe one needs to pass technical inspection to register vehicle, and they measure % of moisture in fluid. That is why all European vehicles are on 2 year schedule.
 
edyvw said:
Bcs. In Europe one needs to pass technical inspection to register vehicle, and they measure % of moisture in fluid. That is why all European vehicles are on 2 year schedule.
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I would be interested in measuring the moisture content of DOT3 fluid after several years. Most of the domestic manufacturers claim moisture absorption is a non-issue nowadays.
 
The Critic said:
I would be interested in measuring the moisture content of DOT3 fluid after several years. Most of the domestic manufacturers claim moisture absorption is a non-issue nowadays.
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it isn’t

the corrosion problem has replaced it and zinc content is the new boogeyman
 
Wheel said:
My understanding is that DOT 4 with more borates creates acids (or at least stronger acids) when contaminated with water. This can cause more corrosion than just the water.
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that's my understanding aswell, the higher the boiling point, the more chance of acid formation. DOT 5.1 is probably even worse
 
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