Someone educate me brake fluid change frequency.
#1
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Someone educate me brake fluid change frequency.
Ok so I understand that brake fluid absorbs moisture and becomes less effective over time. So especially on cars that are being tracked, I get it, it needs to be changed.
Having said that there are many other cars out there which have never had their brake fluid changed and they are fine 10-15 years later.
Can someone educate me on the reason for the frequent changes on our cars and other German brands? I like to keep my cars well maintained, but I like to be educated on why I am doing things.
So what happens if its done every 5 years for instance. Is there some exposure to hoses that degrade? Or is it simply about stopping effectiveness only, because I've never heard of brake fluid abruptly failing.
Educate me.
Having said that there are many other cars out there which have never had their brake fluid changed and they are fine 10-15 years later.
Can someone educate me on the reason for the frequent changes on our cars and other German brands? I like to keep my cars well maintained, but I like to be educated on why I am doing things.
So what happens if its done every 5 years for instance. Is there some exposure to hoses that degrade? Or is it simply about stopping effectiveness only, because I've never heard of brake fluid abruptly failing.
Educate me.
#2
brake fluid attracts and holds moisture...bleeding it purges the moisture out and protects the metal system components. The Euro brands specify it more frequently as many rely on heat capacity of the brake system for Autobahn usage...fresh fluid has a much higher boiling point than old/moisture-laded fluid
#3
Drifting
IIRC Porsche recommends a fluid flush and fill every two years. It's a good thing since in addition to absorbing water a lot of crud can build up in the lines and calipers.
#5
Race Director
Ok so I understand that brake fluid absorbs moisture and becomes less effective over time. So especially on cars that are being tracked, I get it, it needs to be changed.
Having said that there are many other cars out there which have never had their brake fluid changed and they are fine 10-15 years later.
Can someone educate me on the reason for the frequent changes on our cars and other German brands? I like to keep my cars well maintained, but I like to be educated on why I am doing things.
So what happens if its done every 5 years for instance. Is there some exposure to hoses that degrade? Or is it simply about stopping effectiveness only, because I've never heard of brake fluid abruptly failing.
Educate me.
Having said that there are many other cars out there which have never had their brake fluid changed and they are fine 10-15 years later.
Can someone educate me on the reason for the frequent changes on our cars and other German brands? I like to keep my cars well maintained, but I like to be educated on why I am doing things.
So what happens if its done every 5 years for instance. Is there some exposure to hoses that degrade? Or is it simply about stopping effectiveness only, because I've never heard of brake fluid abruptly failing.
Educate me.
Have to point out that for some Porsche models the clutch shares the fluid with the brake system.
Based on my first hand experience with my Boxster and letting its brake fluid go just 2.5 years (lost track of time) without a flush/bleed while the braking action was apparently unaffected as it turned out clutch action was negatively affected.
The symptoms were I was unable to move the car from a stop smoothly no matter how hard I focused on my clutch work. And shifting became crunchy as if I was not depressing the clutch all the way or my timing of when I pushed the clutch pedal down and shifted was off.
An overdue brake/clutch fluid flush/bleed eliminated the problems with the clutch and shifting.
While as I noted above braking action before and after was as far as I could tell the same the transformation of the clutch and shifting action was remarkable and convinced me the 2 year brake fluid flush/bleed is very important.
Even in a Tip/PDK equipped car I see no benefit in skipping this service. I am not anxious to have to deal with brake problems arising from the lack of proper fluid servicing even if braking performance is unaffected. And one might not know braking performance was affected until too late.
#7
Race Director
Thus one should still perform a periodic brake fluid flush/bleed.
Also, synthetic brake fluid is my info primarly used by the military due to its superior low temperature performance. In spite of this there is some indication the military is desirious in moving away from synthetic brake fluid and moving back to DOT 4 fluid. If this happens then synthetic brake fluid could become extinct with the fall off in demand from the military.
This could be a problem as I understand it the recommendation is once one switches to a synthetic brake fluid there is no going back.
There is too the risk of moving to synthetic fluid in an older car. The brake system likely has sludge -- especially if the owner is one who has skipped the regular brake fluid flush/bleed services -- and the synthetic fluid will combine with this sludge and could cause sticky pistons.
There is nothing wrong with good old DOT 4 fluid. All that is needed is a regular flush/bleed and the braking system should perform properly with no other attention for years and years and hundreds of thousands of miles.
Given the risk of moving to a synthetic fluid, along with the necessity of doing a flush at least to push any water out of the calipers, staying with a DOT 4 fluid seems the lesser of two evils.
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#8
Nordschleife Master
All brake fluid even synthetic except dot 5 silicon will absorb water. They sell testers for contamination after 2 years generally your looking at 2% . Cheap fluids will start at 1% always use good fluid I suggest oem ATE products. The water contamination can cause corrosion in the brake pistons as well as cause failure of the abs valves. I have seen both happen if the systems are neglected for to long. I always do mine every 2 years. If your car is kept in climate control you will find most ire contamination isnt as bad or if you live in a place that doesn't see big temp changes.
Last edited by Fishey; 03-29-2016 at 01:14 PM.
#9
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#10
Nordschleife Master
#12
Rennlist Member
While the synthetic brake fluid does not absorb water any water that gets into the system will sink down to the lowest point which has to be the brake calipers/piston area. Upon hard braking and high temperatures the water there will boil at 212F (vs. the ~500F boiling point of synthetic brake fluid) and affect braking.
Thus one should still perform a periodic brake fluid flush/bleed.
Also, synthetic brake fluid is my info primarly used by the military due to its superior low temperature performance. In spite of this there is some indication the military is desirious in moving away from synthetic brake fluid and moving back to DOT 4 fluid. If this happens then synthetic brake fluid could become extinct with the fall off in demand from the military.
This could be a problem as I understand it the recommendation is once one switches to a synthetic brake fluid there is no going back.
There is too the risk of moving to synthetic fluid in an older car. The brake system likely has sludge -- especially if the owner is one who has skipped the regular brake fluid flush/bleed services -- and the synthetic fluid will combine with this sludge and could cause sticky pistons.
There is nothing wrong with good old DOT 4 fluid. All that is needed is a regular flush/bleed and the braking system should perform properly with no other attention for years and years and hundreds of thousands of miles.
Given the risk of moving to a synthetic fluid, along with the necessity of doing a flush at least to push any water out of the calipers, staying with a DOT 4 fluid seems the lesser of two evils.
Thus one should still perform a periodic brake fluid flush/bleed.
Also, synthetic brake fluid is my info primarly used by the military due to its superior low temperature performance. In spite of this there is some indication the military is desirious in moving away from synthetic brake fluid and moving back to DOT 4 fluid. If this happens then synthetic brake fluid could become extinct with the fall off in demand from the military.
This could be a problem as I understand it the recommendation is once one switches to a synthetic brake fluid there is no going back.
There is too the risk of moving to synthetic fluid in an older car. The brake system likely has sludge -- especially if the owner is one who has skipped the regular brake fluid flush/bleed services -- and the synthetic fluid will combine with this sludge and could cause sticky pistons.
There is nothing wrong with good old DOT 4 fluid. All that is needed is a regular flush/bleed and the braking system should perform properly with no other attention for years and years and hundreds of thousands of miles.
Given the risk of moving to a synthetic fluid, along with the necessity of doing a flush at least to push any water out of the calipers, staying with a DOT 4 fluid seems the lesser of two evils.
Last edited by Kevinmacd; 03-29-2016 at 12:36 PM.
#13
Instructor
Silicone based brake fluids tend to entrap air (dissolved air, not air that can be bled out of a brake system). They also tend to expand at significantly lower temps than their actual boiling points. Both of these items lead to soft, spongy pedals. This is why they are not used in performance applications or race cars.
If this was a cure-all, Porsche would have sent the cars out of the factory with silicone based brake fluid.
If this was a cure-all, Porsche would have sent the cars out of the factory with silicone based brake fluid.
#14
Nordschleife Master
Silicone based brake fluids tend to entrap air (dissolved air, not air that can be bled out of a brake system). They also tend to expand at significantly lower temps than their actual boiling points. Both of these items lead to soft, spongy pedals. This is why they are not used in performance applications or race cars.
If this was a cure-all, Porsche would have sent the cars out of the factory with silicone based brake fluid.
If this was a cure-all, Porsche would have sent the cars out of the factory with silicone based brake fluid.
#15
Rennlist Member
Silicone based brake fluids tend to entrap air (dissolved air, not air that can be bled out of a brake system). They also tend to expand at significantly lower temps than their actual boiling points. Both of these items lead to soft, spongy pedals. This is why they are not used in performance applications or race cars.
If this was a cure-all, Porsche would have sent the cars out of the factory with silicone based brake fluid.
If this was a cure-all, Porsche would have sent the cars out of the factory with silicone based brake fluid.
Staying with a high qualty dot4 per Porsche is the way to go for all round performance.
Last edited by Kevinmacd; 03-29-2016 at 12:46 PM.