2 Year Brake Fluid Changes--Overkill?

[2EHA]

water contamination isn’t really a problem. breakdown of corrosion inhibitors is more serious, sometimes brake fluid turns green from all the copper floating around

 

[ctechbob]

I was curious, as brake failure does seem to be the cause of a small percentage of accidents. Looks like there is a 2015 study by the NHTSA:

https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/812115

Of the small percentage (2%) of the crashes in which the critical reason was assigned to the vehicle, the tire problem accounted for about 35 percent (±11.4%) of the crashes. Brake related problems as critical reasons accounted for about 22 percent (±15.4%) of such crashes.

Fluid issues are probably another small % of that, but.....god forbid I'm ever involved in a fatality accident, I want to know I did everything in my power to prevent it.

Its a small number, but a non-zero one. Maintain your braking system peeps.

Side note - I'm not a 'if it only saves one life it is worth it' person. But IMO $10-20 of brake fluid every now and then doesn't fit that.

 

[JHZR2]

Easiest thing is to just drain or siphon out the reservoir, refill with DOT4 (less hygrospcopic, but DOT 3 can work). Drive it and it will mix. Repeat annually.

You can introduce air very easily via the screws if you are not careful; this is so much simpler and highly effective.

What basis do you have to say this is “highly effective”? I find it dubious that this does anything at all, particularly to get the damp, nasty fluid in the caliper (which holds a lot). And, it will not get that nasty fluid out; even if some level of moisture is redistributed/scavenged somehow (again dubious because of the small tubing and long, tortuous path), it won’t get the degraded fluid out of the calipers.

 

[doitmyself]

DOT 4 is more hygroscopic than DOT 3 but its boiling point is higher, that's why some manufacturers used it.

What I read is that DOT 4 is less hygroscopic, but when it does absorb moisture it's boiling resistance drop rate is MUCH faster than DOT 3, so there can be tradeoffs. StopTech and aa1 articles support this theory.

I use what the vehicle mfg. recommends. I don't believe that changing just the reservoir fluid is effective.

 

[totegoat]

I use gears more than brakes and don't have to replace them or fluid during the 100K that I run most vehicles.

 

[Blinker]

I wasn’t sure if I wanted to comment on this thread because I’m not an expert on brake fluid. But ever since vehicles started coming from the factory with DOT 3 and ABS brakes I have stopped changing brake fluid. From my experience it seems GM stopped recommending brake fluid changes around the mid 90’s. With the amount of complexity in an ABS module I’d rather follow the recommendation and leave well enough alone. I wouldn’t be a bit surprised if manufacturers start sealing off the master cylinder like they did with automatic transmissions.

Also, I remember reading a technical bulletin years ago from GM regarding their ACDelco Supreme II brake fluid. The article talked about how it wasn’t just any old DOT 3 fluid. It was designed by GM with extra corrosion inhibitors and some other properties that go above and beyond the DOT 3 specification.

 

[Wolf359]

I use gears more than brakes and don't have to replace them or fluid during the 100K that I run most vehicles.

They don't use brake fluid. Why not say the same with oil? No need to change the oil just because you don't change gear oil. See what happens when you run oil for 100k....

Just not the same. Different system, fluid completely.

 

[02zx9r rev2]

What basis do you have to say this is “highly effective”? I find it dubious that this does anything at all, particularly to get the damp, nasty fluid in the caliper (which holds a lot). And, it will not get that nasty fluid out; even if some level of moisture is redistributed/scavenged somehow (again dubious because of the small tubing and long, tortuous path), it won’t get the degraded fluid out of the calipers.

That has always been my understanding, siphoning fluid out of the master cylinder and replacing with fresh fluid doesn’t really accomplish anything. It will never get down to the calipers. The only way to get the old fluid out is to open the bleeders and flush out the old with new.
I think I recall someone had said once it’s a closed loop system or something like that, it doesn’t circulate like say siphoning out and replacing power steering fluid, I used to to that but now I have e-power steering

 

[nobb]

DOT 4 is more hygroscopic than DOT 3 but its boiling point is higher, that's why some manufacturers used it.

Fresh DOT 4 has a higher BP than DOT 3, so it is a higher performing fluid. However, since DOT 4 is more hydroscopic it's BP rating deteriorates quicker than DOT 3 and could get to a point where it's inferior to DOT 3 entirely. Should not be a problem for people who regular flush out the fluid, but since most people don't I would imagine DOT 3 is better for longevity.

 

[PimTac]

I have never had the brake fluid changed proactively before but times do change. As my Mazda is three years old now I’ll likely get it done at the next service. Mazda recommends every 24 months or 40,000 kilometers which ever comes first.

 

[ctechbob]

I wasn’t sure if I wanted to comment on this thread because I’m not an expert on brake fluid. But ever since vehicles started coming from the factory with DOT 3 and ABS brakes I have stopped changing brake fluid. From my experience it seems GM stopped recommending brake fluid changes around the mid 90’s. With the amount of complexity in an ABS module I’d rather follow the recommendation and leave well enough alone. I wouldn’t be a bit surprised if manufacturers start sealing off the master cylinder like they did with automatic transmissions.

Also, I remember reading a technical bulletin years ago from GM regarding their ACDelco Supreme II brake fluid. The article talked about how it wasn’t just any old DOT 3 fluid. It was designed by GM with extra corrosion inhibitors and some other properties that go above and beyond the DOT 3 specification.

I think you're a little backwards in your logic. A thousand dollar ABS module having to be replaced is a lot more expensive than a master cylinder or caliper. I want fresh fluid with good anti-corrosion additives in my system at all times.

It's my understanding that there are very few ABS modules these days that require special bleeding procedures. Most of them simply require bleeding the calipers as normal.

Again, it all boils down to, how long are you keeping the car. If you're keeping it long term, maintain ALL of the fluids and systems. If you're dumping it after a few years, your call, whatever is in it will go that distance unless you're in a SEVERE service schedule (Racing, AutoX, Etc).

 

[Oro_O]

What basis do you have to say this is “highly effective”? I find it dubious that this does anything at all, particularly to get the damp, nasty fluid in the caliper (which holds a lot). And, it will not get that nasty fluid out; even if some level of moisture is redistributed/scavenged somehow (again dubious because of the small tubing and long, tortuous path), it won’t get the degraded fluid out of the calipers.

The fluids mix fully. Brownian motion.

If you do the reservoir, you will drop a 4% (water content) system to 2%, do it twice and you drop to 1%. It's the same as a partial drain/fill in any system, really. It's tested, and works. You can demonstrate this yourself in your driveway with calcium hydride strips or test pens. Over time (and it's not a lot), the water content in the calipers will equal the content in the reservoir.

 

[JHZR2]

The fluids mix fully. Brownian motion.

If you do the reservoir, you will drop a 4% (water content) system to 2%, do it twice and you drop to 1%. It's the same as a partial drain/fill in any system, really. It's tested, and works. You can demonstrate this yourself in your driveway with calcium hydride strips or test pens. Over time (and it's not a lot), the water content in the calipers will equal the content in the reservoir.

so you have data you can provide where you took sequential samples, at the calipers, with no other removal of fluid besides the tiny droplet sample, and saw a real chemical basis of change?

I’ll reserve my doubts but entertain data.

To me, this sounds like draining your coolant bottle and topping it up, and assuming that the inhibitors will be replaced suitably over time... which forgets other reasons for exchange.

I also have seen gunk built up in brake fluid systems, and your process would not resolve that

 

[nthach]

I do three years with good DOT4 or every brake pad swap. If you drive in hilly areas or stop and go, I might recommend more frequent service.

 

[Blinker]

I think you're a little backwards in your logic. A thousand dollar ABS module having to be replaced is a lot more expensive than a master cylinder or caliper. I want fresh fluid with good anti-corrosion additives in my system at all times.

It's my understanding that there are very few ABS modules these days that require special bleeding procedures. Most of them simply require bleeding the calipers as normal.

Again, it all boils down to, how long are you keeping the car. If you're keeping it long term, maintain ALL of the fluids and systems. If you're dumping it after a few years, your call, whatever is in it will go that distance unless you're in a SEVERE service schedule (Racing, AutoX, Etc).

I keep all my vehicles to at least 200k miles. Haven’t changed brake fluid since the early 90’s. Haven’t had an ABS controller failure, nor had to replace any brake hoses or caliper pistons. I’ll keep doing what I’ve been doing.

 

[Blinker]

so you have data you can provide where you took sequential samples, at the calipers, with no other removal of fluid besides the tiny droplet sample, and saw a real chemical basis of change?

I’ll reserve my doubts but entertain data.

To me, this sounds like draining your coolant bottle and topping it up, and assuming that the inhibitors will be replaced suitably over time... which forgets other reasons for exchange.

I also have seen gunk built up in brake fluid systems, and your process would not resolve that

Why must you not accept other people’s point of view?

FWIW Prestone says that a master cylinder turkey baster flush is an adequate flush. I also wouldn’t be a bit surprised if a majority of car dealerships consider a brake fluid flush to be nothing more than a turkey baster flush and call it a day.

Braking systems are much more durable than they were in the days of the 1960’-1970’s.

 

[JHZR2]

Why must you not accept other people’s point of view?

FWIW Prestone says that a master cylinder turkey baster flush is an adequate flush. I also wouldn’t be a bit surprised if a majority of car dealerships consider a brake fluid flush to be nothing more than a turkey baster flush and call it a day.

Braking systems are much more durable than they were in the days of the 1960’-1970’s.

The point on here is to look for data and discuss.

Please show me where a factory service manual says that replacing the fluid at the reservoir is sufficient.

Everywhere I look, I can’t seem to find indication that brownian motion is sufficient, so just extract and replace what’s in the reservoir. Brake fluid doesn’t circulate. It’s not well mixed. The paths through narrow piping further hinder all this, and if that’s not enough, the use of solenoid and check valves in the ABS system should also concern you regarding this hypothesis. And remember, it’s not just water, but copper that catalyzes other reactions in the system.

I get instructions like this:

As I stated, I reserve my doubts but welcome data

 

[edyvw]

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.

Bcs. in Europe they measure moisture level in break fluid during technical inspection required for registration. If you are at 3% and up, you are out.

 

[Retirednow]

Used to do them annually. 2 years max

 

[The Critic]

I wasn’t sure if I wanted to comment on this thread because I’m not an expert on brake fluid. But ever since vehicles started coming from the factory with DOT 3 and ABS brakes I have stopped changing brake fluid. From my experience it seems GM stopped recommending brake fluid changes around the mid 90’s. With the amount of complexity in an ABS module I’d rather follow the recommendation and leave well enough alone. I wouldn’t be a bit surprised if manufacturers start sealing off the master cylinder like they did with automatic transmissions.

Also, I remember reading a technical bulletin years ago from GM regarding their ACDelco Supreme II brake fluid. The article talked about how it wasn’t just any old DOT 3 fluid. It was designed by GM with extra corrosion inhibitors and some other properties that go above and beyond the DOT 3 specification.

https://static.nhtsa.gov/odi/tsbs/2014/MC-10112028-9999.pdf

There is a new bulletin on the ACDelco Supreme III Brake Fluid.

"There is a New DOT 3 brake fluid for the 2014 Silverado and Sierra 1500. The New DOT 3 brake fluid is available for order via your Parts Department as follows:

GM P/N 19299818 (U.S.)
GM P/N 19299819 (Canada)

The new fluid has significant improvements in lubricity to eliminate previous known issues with master cylinder squeak/noise.
Always use the New DOT 3 brake fluid when refilling or servicing the brake system.

Additional Info:

If another type of DOT 3 brake fluid (including the GM DOT 3 Delco Supreme II) is used to refill the master cylinder, it may cause a master cylinder squeak noise. If the wrong DOT 3 brake fluid is used, remove as much of the old brake fluid from the master cylinder as possible and refill with the New DOT 3 brake fluid. Depress and release the brake pedal five times to allow the new fluid to enter the system. "

I have always suspected that not all DOT3 Brake Fluids are created equal. I do think some of the OE fluids may contain additional properties beyond the typical aftermarket DOT3 brake fluids. Whether this has an impact on service life is debatable, but I have noticed that some OE brake fluids (e.g. Toyota) stay clear for a very long time.