I know it's recommended to replace brake fluid every 2 years. I was curious as to if it's because of breakdown, or contaminates? or both.
Brake Fluid Changes...
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It's because it absorbs moisture. Eventually that moisture lowers the boiling point of the fluid, and allows corrosion.
every 2 yrs is the mostly recommended AVERAGE time..moisture in the fluid becomes a problem for stopping in high stress situations or it shortens the life of the calipers, especially the rear ones, since moisture likes to migrate to the rear and rust developes within the piston areas thus seizing the calipers... if you live in a high moist area, yearly is recommended...I have changed many calipers over the years for friends and family and have yet to change any on my herd of cars..mostly what I drive is between 20-30 yrs old and all is still working as should...on any ABS equipped car I change the fluid yrly, since it is so easy to do when rotating the tires..pick your method..speed bleeders/ your friend wife etc to pump the brakes or a suction pump..when you get the hang of it ..it is very simple to do...
agree with the above post regarding moisture. for me, i switch brake fluid colors to make it easier to tell when the old fluid is finished and the new fluid is coming out. so i do amber, blue, amber, blue, etc...
Fair enough. being a closed system, I wouldn't think it would pick up much moisture... I do it anyway, but I wasn't sure as to why.
Originally Posted By: WMSmotorhead
Fair enough. being a closed system, I wouldn't think it would pick up much moisture... I do it anyway, but I wasn't sure as to why.
...the chemical makeup of brake fluid wants to attract moisture..it is not really a closed system...yes it will keep dirt out but not moisture which can travel thru plastic and rubber...clear brake fluid is not an indication of not having to much moisture in the fluid..even an unopened plastic container sitting on the store shelf may not be what you want if sitting for many years...
Fair enough. being a closed system, I wouldn't think it would pick up much moisture... I do it anyway, but I wasn't sure as to why.
...the chemical makeup of brake fluid wants to attract moisture..it is not really a closed system...yes it will keep dirt out but not moisture which can travel thru plastic and rubber...clear brake fluid is not an indication of not having to much moisture in the fluid..even an unopened plastic container sitting on the store shelf may not be what you want if sitting for many years...
I did my brake fluid just this year for the first time on my 2008 xB... A bit overdue, I am sure. The fluid came out honey-colored and the new fluid is as clear as water. It definitely had absorbed its share of dirt/water/whatever else.
It's easy enough to do though. I plan on doing it every year in spring most likely, along with servicing the slide pins and everything else.
It's easy enough to do though. I plan on doing it every year in spring most likely, along with servicing the slide pins and everything else.
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Originally Posted By: WMSmotorhead
... being a closed system, I wouldn't think it would pick up much moisture...
If you study seals and how they work, you'll find they are imperfect on the micro level. Over time moisture gets in past the caliper seal, right where you don't want it to corrode. Couple that with a cast iron surface, and you have a situation that needs maintenance.
... being a closed system, I wouldn't think it would pick up much moisture...
If you study seals and how they work, you'll find they are imperfect on the micro level. Over time moisture gets in past the caliper seal, right where you don't want it to corrode. Couple that with a cast iron surface, and you have a situation that needs maintenance.
In addition to the above concerns over moisture content, vapor lock, and corrosion:
DOT 4 brake fluids with borate esters will not only absorb moisture, but will hydrolyze into boric acid, not good for your brake system. I would almost recommend shortening that 2 year interval further if I was using DOT 4 fluid.
DOT 4 brake fluids with borate esters will not only absorb moisture, but will hydrolyze into boric acid, not good for your brake system. I would almost recommend shortening that 2 year interval further if I was using DOT 4 fluid.
Originally Posted By: WMSmotorhead
I know it's recommended to replace brake fluid every 2 years. I was curious as to if it's because of breakdown, or contaminates? or both.
Well then, you don't agree with GM, who says about 7 years initially.
No harm in 2 year changes. Water contamination is very over rated in brake systems, which are closed systems.
But particulate matter can accumulate.
I know it's recommended to replace brake fluid every 2 years. I was curious as to if it's because of breakdown, or contaminates? or both.
Well then, you don't agree with GM, who says about 7 years initially.
No harm in 2 year changes. Water contamination is very over rated in brake systems, which are closed systems.
But particulate matter can accumulate.
Originally Posted By: mechtech2
Well then, you don't agree with GM, who says about 7 years initially.
No harm in 2 year changes. Water contamination is very over rated in brake systems, which are closed systems.
But particulate matter can accumulate.
Actually, glad you mentioned that. Many times when I get an older abused car, you can see rust in the brake fluid... THAT's what I was thinking the bigger deal was... but then again, did the rust come from the moisture....
Round and Round we go.
Well then, you don't agree with GM, who says about 7 years initially.
No harm in 2 year changes. Water contamination is very over rated in brake systems, which are closed systems.
But particulate matter can accumulate.
Actually, glad you mentioned that. Many times when I get an older abused car, you can see rust in the brake fluid... THAT's what I was thinking the bigger deal was... but then again, did the rust come from the moisture....
Round and Round we go.
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I understand there can be some seal incompatibilities that prevent using DOT4 or higher when DOT3 was the OEM choice, but how can I find out if my system can use DOT4?
Anyone have any ideas? I am due to change my fluid soon and it came with DOT3. If DOT3 is all that can be used, is there a "best" fluid?
Anyone have any ideas? I am due to change my fluid soon and it came with DOT3. If DOT3 is all that can be used, is there a "best" fluid?
I've got Dot3 on all my cars.
Originally Posted By: 2010_FX4
I understand there can be some seal incompatibilities that prevent using DOT4 or higher when DOT3 was the OEM choice, but how can I find out if my system can use DOT4?
Anyone have any ideas? I am due to change my fluid soon and it came with DOT3. If DOT3 is all that can be used, is there a "best" fluid?
I used DOT4 in LS400 for some years, now I use DOT3 in all my cars, including in the E430 which recommends DOT4.
For daily drive there is no difference that I can detect, the braking distance is the same and no sign of DOT3 boiling off. All my brake system are working well with either DOT4 or DOT3.
If you do a lot of towing on hilly terrain, then DOT4 will be better with higher boiling point.
I understand there can be some seal incompatibilities that prevent using DOT4 or higher when DOT3 was the OEM choice, but how can I find out if my system can use DOT4?
Anyone have any ideas? I am due to change my fluid soon and it came with DOT3. If DOT3 is all that can be used, is there a "best" fluid?
I used DOT4 in LS400 for some years, now I use DOT3 in all my cars, including in the E430 which recommends DOT4.
For daily drive there is no difference that I can detect, the braking distance is the same and no sign of DOT3 boiling off. All my brake system are working well with either DOT4 or DOT3.
If you do a lot of towing on hilly terrain, then DOT4 will be better with higher boiling point.
Originally Posted By: jake88
In addition to the above concerns over moisture content, vapor lock, and corrosion:
DOT 4 brake fluids with borate esters will not only absorb moisture, but will hydrolyze into boric acid, not good for your brake system. I would almost recommend shortening that 2 year interval further if I was using DOT 4 fluid.
Do you care to share which brands use borate esters?
In addition to the above concerns over moisture content, vapor lock, and corrosion:
DOT 4 brake fluids with borate esters will not only absorb moisture, but will hydrolyze into boric acid, not good for your brake system. I would almost recommend shortening that 2 year interval further if I was using DOT 4 fluid.
Do you care to share which brands use borate esters?
The best way is these strips they make and you dip into the master cylinder. When it changes to a certain color, it indicates copper which is the first metal to spike when the brake fluid has lost its ability to prevent corrosion. Then you change it out.
To my knowledge all the DOT 4 fluids have borate esters. Also, those OEMs that specify a 2 year interval are probably also speccing for DOT 4 fluids. I think the majority of luxury brands and European brands use the DOT 4 fluids.
Also, the copper-detecting strips are a very good idea as mentioned above.
Also, the copper-detecting strips are a very good idea as mentioned above.
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