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911 Brake Fluid Flush - How often?

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Old Dec 1, 2020 | 10:09 PM
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Question 911 Brake Fluid Flush - How often?

No listing in manual for 991.2 (MY2019 C2S)

For Macan, Porsche has every 2 years regardless of miles in service schedule. For 911, it is not mentioned.

I am ~ 1 month away from 2 year oil change & I tested % water & it is 0%.

I’m in a dry climate.

I have seen nothing re problems with brake fluid other than moisture content, which of course is an issue & the main reason to change it.

I have also heard that since brake fluid does not circulate, measuring water % at the brake fluid reservoir does not give you a true test of the moisture content at the calipers & elsewhere in the system.
It may not circulate but, I assume it mixes some.

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Old Dec 1, 2020 | 10:31 PM
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I believe it’s also recommended at 2 years for the 991.
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Old Dec 1, 2020 | 10:32 PM
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My Indy does the moisture test and either replaces the fluid or says everything is OK....I tend to go three years based on the last 4 Porsche’s.
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Old Dec 2, 2020 | 02:58 AM
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The manual says 2 years but I think it's overkill. If you track it, you'll probably want to flush it more often. Mine is exactly 2 years old. I tested for water in the brake fluid and came out 0%. I'll give it another year and see.
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Old Dec 2, 2020 | 07:35 AM
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Set aside your brake fluid for a moment. Why is your oil 2 years old? That's a bigger issue.
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Old Dec 2, 2020 | 08:35 AM
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Originally Posted by TwinTurbo420
No listing in manual for 991.2 (MY2019 C2S)
I don't think any of this kind of stuff is listed in the Owner's Manual. These things are listed in a separate thinner booklet dedicated to Maintenance Schedules and a place for the dealerships to put their service stamps. Maybe yours is missing? If it is, they are easy to pick-up on eBay.
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Old Dec 2, 2020 | 08:41 AM
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Originally Posted by LexVan
Set aside your brake fluid for a moment. Why is your oil 2 years old? That's a bigger issue.
Lex, I think he meant "second oil change" which is on his second year of ownership. I could be wrong.
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Old Dec 2, 2020 | 08:55 AM
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Brake fluid change frequency totally depends on usage. Testers are cheap. Test and it’s easy and cheap to change with a $100 investment in a pressure bleeder.

I’d still do every 2-3 years. Here’s the issue with water, it boils and evaporates which will let air into the system.
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Old Dec 2, 2020 | 10:02 AM
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Originally Posted by garfunkle
Brake fluid change frequency totally depends on usage. Testers are cheap. Test and it’s easy and cheap to change with a $100 investment in a pressure bleeder.

I’d still do every 2-3 years. Here’s the issue with water, it boils and evaporates which will let air into the system.
This ^^^^ is only partially accurate. Brake fluid is hydroscopic (naturally attracts moisture). Overtime its H2O content as a percentage of fluid will increase due to ambient humidity. The brake fluid system is not air tight. The higher H2O saturation, the lower the boiling point of the fluid. If the fluid should boil as a result of heating the fluid through braking, the fluid becomes gaseous. The boiling process will create the gases and brakes will be compromised.
If one engages in regular spirit driving, track driving or similar driving it is advisable to change fluid every year. For example, I have taken readings of my fluid and ranged >1% but <2% H2O and found my brakes compromised (mushy) during heavy continuous braking. Brake fluid testers are good for information, but it all depends on the heat the system generates and the amount of H20 saturation.
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Old Dec 2, 2020 | 11:35 AM
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Porsche is very aggressive with their maintenance schedule especially for plugs and brake fluid flush.

if I track or drive very very hard 20 weekends per year in my 911 I understand. If you drive it like your Toyota Corolla most of the time and only so often get on it, is it needed?? You should be able to determine what is beat for you and your car.

for my Cayenne, never over 80, smooth acceleration and breaking, my maintenance schedule should be similar to a Lexus/BMW plan with plugs, brake fluid flush etc etc etc. every 4- 6 years pending the service. Extra service means $$$$$$ for dealers. I do ensure I do oil change per the warning in the dash for the Cayenne.
For my 911 I follow the Porsche schedule or even more aggressive if I track it

Last edited by Norge911; Dec 2, 2020 at 11:38 AM.
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Old Dec 2, 2020 | 01:23 PM
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Originally Posted by Norge911
Porsche is very aggressive with their maintenance schedule especially for plugs and brake fluid flush.
True, but for some weird reason the US cars "need" service MORE than the cars in Europe. Every 2 years or 20,000 miles in Europe. Every year or 10,000 miles in the US.

I never understood that.
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Old Dec 2, 2020 | 01:38 PM
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Originally Posted by spiderv6
True, but for some weird reason the US cars "need" service MORE than the cars in Europe. Every 2 years or 20,000 miles in Europe. Every year or 10,000 miles in the US.

I never understood that.
Different warranties.
Different fuels.
Different lawyers.

These 3 come to mind first.
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Old Dec 2, 2020 | 02:26 PM
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Originally Posted by LexVan
Different lawyers.
Different lawyers.
Different lawyers.

These 3 come to mind first.
That makes more sense
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Old Dec 2, 2020 | 02:30 PM
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Originally Posted by spiderv6
That makes more sense

I
C
Whut
U
Did
There
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Old Dec 2, 2020 | 03:47 PM
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I'm pretty sure that brake fluid changes are recommended by nearly all vehicle manufacturers every 2 years (not by mileage).
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