When to replace brake fluid - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

D-rek07 · 02-20-2018, 01:56 PM

After quite a bit of research, I cannot find when the actual time to change brake fluid. Everyone just says, "after 2 track days" or "every six months" or something like that. Is there a test or an analysis you can do to determine that it needs to be changed?

Thanks in advance

Code Monkey · 02-20-2018, 02:04 PM

Whenever the brake pedal gets squishy.

strat61caster · 02-20-2018, 02:07 PM

"brake fluid test strips"

A bleed and topping off of fluid every 1-2x track days is cheap insurance, the strips to confirm that at least what's in the reservoir hasn't broken down.

tyler_win_photo · 02-20-2018, 02:08 PM

You can use a brake fluid moisture test kit. They come in strips or you can buy an electronic tester. It's sometimes hard to gauge how squishy your pedal can become over time... unless it's like right after a track day.

If you're not driving it too hard around every 30k is about right.

Tcoat · 02-20-2018, 02:08 PM

Take a look at it. It should be almost clear. If milky, rusty coloured, or blackish then it needs to be changed. It should smell sort of sweetish (hard to describe an odour) and if there is any hint of a burnt smell it should be changed and flushed.

Everybody drives differently so there is no hard and fast time limits or operating condition that says "change it now". Rules of thumb is the harder you drive the car the more often you need to check it.

churchx · 02-20-2018, 02:16 PM

If braking heatload has never been to squishy/fading brakes and to boiled fluid, imho it may last long enough, at least i'd change never boiled fluid at most once per year. But then again if track is mentioned .. it's easy to abuse brakes above their capacity

. BTW, if you boil them often enough, maybe worth considering instead of frequent flushes change fluid to one with higher boiling temps / enhance cooling (eg. airducts) / reduce braking heat load (eg. shorter sessions / pedal dance instead of with nannies / braking lessons by hpde instructors ) .. or move to BBK.

CSG Mike · 02-20-2018, 02:31 PM

Quote:

Originally Posted by D-rek07

After quite a bit of research, I cannot find when the actual time to change brake fluid. Everyone just says, "after 2 track days" or "every six months" or something like that. Is there a test or an analysis you can do to determine that it needs to be changed?

Thanks in advance

Squishy pedal? Change it. Fluid is not amber? Change it. 2 years old? Change it.

Or use Project Mu. Green turns clear if it absorbs too much moisture (aging), or turns brown if it gets too hot (tracking).

PM to order.

Don't forget to bleed your clutch pedal every 2 years too.

guybo · 02-20-2018, 03:45 PM

I switched to Motul at 30k, made a huge difference. It was easy to do and not all that expensive.

D-rek07 · 02-20-2018, 04:57 PM

I track it about once every other month. I have heard about the moisture test strips but is there any other way to test it for being broken down? I'm not really even sure if brake fluid breaks down from heat cycling. I have three track sessions on my current brake fluid and bled them about 6 months ago. I have not noticed any decrease in pedal feel. I'm using Motul RBF600.

CSG Mike · 02-20-2018, 05:25 PM

Quote:

Originally Posted by D-rek07

I track it about once every other month. I have heard about the moisture test strips but is there any other way to test it for being broken down? I'm not really even sure if brake fluid breaks down from heat cycling. I have three track sessions on my current brake fluid and bled them about 6 months ago. I have not noticed any decrease in pedal feel. I'm using Motul RBF600.

Test strips are the objective test. Pedal feel is the subjective test. There is no other way to test, unless your fluid has a provision to indicate moisture.

D-rek07 · 02-20-2018, 05:31 PM

Quote:

Originally Posted by CSG Mike

Test strips are the objective test. Pedal feel is the subjective test. There is no other way to test, unless your fluid has a provision to indicate moisture.

So moisture is the only thing harmful to brake fluid? It can't break down due to heat?

CSG Mike · 02-20-2018, 06:08 PM

Quote:

Originally Posted by D-rek07

So moisture is the only thing harmful to brake fluid? It can't break down due to heat?

Fluid degredation from heat is an indicator that the *real* solution to your problem is to increase capacity with a well designed BBK.

Band-aid fixes include higher grade brake fluid.

D-rek07 · 02-20-2018, 06:47 PM

Quote:

Originally Posted by CSG Mike

Fluid degredation from heat is an indicator that the *real* solution to your problem is to increase capacity with a well designed BBK.

Band-aid fixes include higher grade brake fluid.

So either that or flushing brake fluid more often. I don't think a BBK is necessary for this lightweight car. I have no problem flushing brake fluid, I'm just trying to figure out how to determine that the fluid has degraded from heat.

CSG Mike · 02-20-2018, 06:59 PM

Quote:

Originally Posted by D-rek07

So either that or flushing brake fluid more often. I don't think a BBK is necessary for this lightweight car. I have no problem flushing brake fluid, I'm just trying to figure out how to determine that the fluid has degraded from heat.

How many pads do you have to burn up and how many times do you have to flush fluid, before you've covered the cost of a BBK and then some?

Why does Subaru now provide a factory Brembo setup if it's unnecessary?

02-20-2018, 01:56 PM	#1
D-rek07 Senior Member Join Date: Jan 2017 Drives: 2013 BRZ Location: Orange County Posts: 144 Thanks: 10 Thanked 45 Times in 33 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	When to replace brake fluid After quite a bit of research, I cannot find when the actual time to change brake fluid. Everyone just says, "after 2 track days" or "every six months" or something like that. Is there a test or an analysis you can do to determine that it needs to be changed? Thanks in advance

02-20-2018, 02:08 PM	#4
tyler_win_photo Senior Member Join Date: Dec 2013 Drives: 2014 Scion FRS (Asphalt) Location: Redmond, WA Posts: 554 Thanks: 36 Thanked 171 Times in 141 Posts Mentioned: 6 Post(s) Tagged: 2 Thread(s)	You can use a brake fluid moisture test kit. They come in strips or you can buy an electronic tester. It's sometimes hard to gauge how squishy your pedal can become over time... unless it's like right after a track day. If you're not driving it too hard around every 30k is about right. __________________ AVO Stage 2 Turbo Build Thread https://wheelwell.com/tyler-nguyen-1...014-scion-fr-s

02-20-2018, 02:08 PM	#5
Tcoat Senior Member Join Date: Jul 2014 Drives: 2020 Hakone Location: London, Ont Posts: 69,845 Thanks: 61,656 Thanked 108,283 Times in 46,456 Posts Mentioned: 2495 Post(s) Tagged: 50 Thread(s)	Take a look at it. It should be almost clear. If milky, rusty coloured, or blackish then it needs to be changed. It should smell sort of sweetish (hard to describe an odour) and if there is any hint of a burnt smell it should be changed and flushed. Everybody drives differently so there is no hard and fast time limits or operating condition that says "change it now". Rules of thumb is the harder you drive the car the more often you need to check it. __________________ Racecar spelled backwards is Racecar, because Racecar.

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02-20-2018, 02:04 PM	#2
Code Monkey Senior Member Join Date: Jul 2016 Drives: Subaru BRZ Location: Atlanta, GA Posts: 838 Thanks: 868 Thanked 562 Times in 337 Posts Mentioned: 4 Post(s) Tagged: 0 Thread(s)	Whenever the brake pedal gets squishy.

02-20-2018, 02:16 PM	#6
churchx Senior Member Join Date: Mar 2015 Drives: 2014 GT86 Location: Latvia, Riga Posts: 4,333 Thanks: 696 Thanked 2,085 Times in 1,436 Posts Mentioned: 53 Post(s) Tagged: 1 Thread(s)	If braking heatload has never been to squishy/fading brakes and to boiled fluid, imho it may last long enough, at least i'd change never boiled fluid at most once per year. But then again if track is mentioned .. it's easy to abuse brakes above their capacity . BTW, if you boil them often enough, maybe worth considering instead of frequent flushes change fluid to one with higher boiling temps / enhance cooling (eg. airducts) / reduce braking heat load (eg. shorter sessions / pedal dance instead of with nannies / braking lessons by hpde instructors ) .. or move to BBK.

02-20-2018, 03:45 PM	#8
guybo Huge E85 fan! Join Date: May 2016 Drives: 2016 Scion FRS Location: Tampa, FL, USA Posts: 1,850 Thanks: 539 Thanked 1,010 Times in 605 Posts Mentioned: 32 Post(s) Tagged: 0 Thread(s)	I switched to Motul at 30k, made a huge difference. It was easy to do and not all that expensive.

02-20-2018, 04:57 PM	#9
D-rek07 Senior Member Join Date: Jan 2017 Drives: 2013 BRZ Location: Orange County Posts: 144 Thanks: 10 Thanked 45 Times in 33 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	I track it about once every other month. I have heard about the moisture test strips but is there any other way to test it for being broken down? I'm not really even sure if brake fluid breaks down from heat cycling. I have three track sessions on my current brake fluid and bled them about 6 months ago. I have not noticed any decrease in pedal feel. I'm using Motul RBF600.

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