2 Year Brake Fluid Changes--Overkill?

[supton]

I do every one or two years. IMO a little but often means I don't have to worry about getting every drop out of the lines. I usually bust apart the brakes every spring and relube, and that makes for a good time to pull fluid from each corner. Again, little but often, that means I don't care what corner I start at, as the "old" fluid isn't somehow old and used up (or full or whatever damaging metric you'd prefer).

But in many ways this is overkill--most vehicles go 10+ years without an issue. Also I've not found it to completely prevent the need for new calipers, around here road salt kills everything anyhow.

 

[edyvw]

You guys have to stop using term: in many vehicles.
this is large country with different topography. Demand on brakes is not the same in Colorado and Florida. In Florida one might get away with poor fluid, in CO, not so much.

 

[Blinker]

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.

Thank you for posting that article, it’s very informative. I actually didn’t even know GM had a DOT 3 Supreme III now. I did know that GM Supreme brake fluid has always been touted as superior to other DOT fluids.

Also of note, the GM article says to replace as much fluid as possible in the master cylinder and refill with Supreme III, then depress the brake pedal several times to allow the new fluid to enter the system. This to me shows that master cylinder turkey baster flushes are more than adequate. I firmly believe most dealer brake line flushes are nothing more than the turkey baster flush.

 

[14Accent]

I'll be the first to admit, I'm not a huge proponent of brake flushes. Sure, they're just fine as preventative maintenance but for the most part it's a fluid that's more than capable of doing it's job over the long haul (unless it's abused, like any other fluid regardless of "service life").

That being said, doing regular brake flushes in a state like MN can save a lot of headaches down the road. If nothing else, taking the bleeder screws out completely at the first flush and coating the threads with anti-seize will do wonders for further flushes. That being said, no amount of fluid flushes will counteract the issues that a climate like ours presents on brake components. Rust being the #1.

I rarely have an issue with any fluid-related component in the brake system. It's always a slide issue, a cable issue, a rusted hose or line, seized pads, something like that. I do see the occasional failed piston seal, but that's usually on aluminum rear calipers.

 

[meep]

They won't fail, but braking performance will be reduced, also if high in water/humidity this may rust the sensitive sensors of the ABS system. In the end it's your life, brakes & tires are what keeps you safe.

So, just out of a keen bitog discussion, I’ll challenge you on the statement that “braking performance will be reduced.” In what way?

here’s why I ask. Were a blended family here.... 2 adults, 4 kids. Plus I help friends and volunteer with some guys who work on cars at a local church. And I take care of nearby family. Nobody ever does brake maintenance, so that’s an easy thing for me to help them out with. As you can imagine, we drive used cars, and I’ve bled/changed brake fluid for 35 years. When I swap brake fluid on someone else’s vehicle, and that fluid looks like coffee, there is indeed a difference at the pedal. The new fluid feels more “fluid” or smooth in operation. It might feel a touch more firm. In terms of stopping power, I can’t tell a difference. Pound for pound at the pedal, assuming nothing else changed, the stopping power is, as far as I notice, unchanged. So, how do you define, “performance”?

changing, as reality dictates for me, every 4 years or so, it’s still in good enough shape here that I can’t discern much of a pedal feel difference.

as a bitoger, the pedal feel alone I would agree with you and call that improved performance. But quantitatively that’s a stretch. Am I missing something?

I completely agree that fluid stores moisture, moisture begets rust, begets damage such as seized calipers, etc.. , but I simply haven’t experienced that here. the vehicles I have seen with rusted caliper bores were generally a good bit over 100,000 miles if they were more modern, or over 60,000 back in the 80’s. In either case, the fluid looked really bad.

also, just for accuracy of thought, brake fluid has zero to do with ABS sensors. They dont come into contact with each other unless there’s a problem. Did you mean something else?

*********

side note .... another difference between dot 3 and dot 4, which I’m always surprised doesn’t come up in these threads (which makes me wonder if many people experiment with switching “up” to dot 4 when allowed by the oem), dot 3 has a firmer pedal feel. It’s not especially pronounced, but I noticed it every time. After doing this a few times, I’ve fallen back to using dot 3 unless 4 is required.

be safe!
-m

 

[Pew]

side note .... another difference between dot 3 and dot 4, which I’m always surprised doesn’t come up in these threads (which makes me wonder if many people experiment with switching “up” to dot 4 when allowed by the oem), dot 3 has a firmer pedal feel. It’s not especially pronounced, but I noticed it every time. After doing this a few times, I’ve fallen back to using dot 3 unless 4 is required.

Placebo effect. There's no difference in pedal feels between the two types of fluid, only dry and wet boiling points.

 

[meep]

I’d like to believe that, but experienced with 2 Subarus and an S10, and the S10 owner noted it as well. The Critic on this site has noticed it as well, though IIRC he indicated nobody else he’s discussed it with has noted it. Maybe it’s more notable on certain makes than others? All the ones I tried this with were 90s models.

 

[twouvakind]

Brake fluid is cheap X's 24 months. And your owners manual say's to do so.

 

[Jetronic]

Still waiting for Overkill to share his thoughts in this thread...

 

[Wolf359]

I’d like to believe that, but experienced with 2 Subarus and an S10, and the S10 owner noted it as well. The Critic on this site has noticed it as well, though IIRC he indicated nobody else he’s discussed it with has noted it. Maybe it’s more notable on certain makes than others? All the ones I tried this with were 90s models.

Going to say it's the placebo effect. It's a fluid that can't be compressed. As to performance degradation, that would depend on whether the water boils or not. Otherwise it's still a liquid until it hits the boiling point, then it's a gas that can be compressed. Maybe the bleeding of the brakes gets rid of any air in the lines and makes the pedal feel firmer no matter what fluid is in there.

 

[meep]

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.

 

[meep]

Here it is. look half way down the page. I know we’re all just guys on the internet who dig doing and sharing about this stuff... and it’s only by words that we evaluate each other’s credibility.... so I’ll reference The Critic here as he is well respected here.

https://bobistheoilguy.com/forums/t...-to-dot3-over-dot4.302342/page-2#post-4996959

 

[Pew]

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.

Should be the same viscosity per specifications.

 

[meep]

ok... yeah, pretty close.

mich respect, Pew, Wolf.

m

 

[Jetronic]

Going to say it's the placebo effect. It's a fluid that can't be compressed. As to performance degradation, that would depend on whether the water boils or not. Otherwise it's still a liquid until it hits the boiling point, then it's a gas that can be compressed. Maybe the bleeding of the brakes gets rid of any air in the lines and makes the pedal feel firmer no matter what fluid is in there.

The notion that fluids can not be compressed is wrong. The compressibility is very (extremely) low and in most any case not a concern but there's a few systems that rely on the compressibility of fluids... Common rail diesel for one.

DOT 5 (silicone) brake fluid is quite compressible even, and even with fresh fluid leads to a soft pedal.

The issue with regular brake fluid is that it becomes more compressible with water contamination and this goes to extremes if the water has become steam at some point.

 

[The Critic]

ok... yeah, pretty close.

mich respect, Pew, Wolf.

m

I have noticed DOT3 delivers a somewhat firmer pedal, but most people are not able to discern the difference. I have a feeling that it may be related to the components of the individual brake fluid than the type of fluid. DOT4 does have a higher viscosity at very low temps but I do not think my climate conditions would have allowed this property to become evident.

Regardless, I have yet to find an explanation for this behavior.

 

[MrPlow]

I only change the brake fluid when changing the brakes. LOL
With OEM quality pads, my front brakes on my main truck can go over 60K miles. Fluid changes were not very frequent.

I live in a place with lots of hills and have driven up and down steep logging roads in the mountains for decades. I've never had any issues with my brakes. But, with that said, the brakes usually feel a bit more firm after a full service.

I did purchase one of those brake bleeder bottles with a check valve recently. Supposed to make it go very quick with one person doing the work. Haven't used it yet. Are these things any good? Also got a turkey baster for draining the reservoir.

 

[Luftmasse]

I have noticed DOT3 delivers a somewhat firmer pedal, but most people are not able to discern the difference. I have a feeling that it may be related to the components of the individual brake fluid than the type of fluid. DOT4 does have a higher viscosity at very low temps but I do not think my climate conditions would have allowed this property to become evident.

Regardless, I have yet to find an explanation for this behavior.

When you say DOT 3, are you refering to OEM or Aftermarket?

 

[The Critic]

When you say DOT 3, are you refering to OEM or Aftermarket?

I no longer recall the specifics, it has been awhile since this happened.

 

[Gimpy1]

Here is an "experiment" to see if it overkill or not. Buy some brake fluid test strips ( Amazon i like the phoenix systems ones since they also make coolant strips) and test your brake fluid. Brake fluid is hygroscopic and water reduces the boiling point but you also have to consider the amount of copper in the system. I have yet to have brake fade on my personal vehicles which include a pontiac gto driven in mexico city in the moutains. It may or may not be overkill but are you willing to risk it and chance an accident.