How Often Do You Flush/Change Brake Fluid?
Thread Starter
Pro
Joined: Jul 2006
Posts: 505
Likes: 25
From: Buxton Maine
How Often Do You Flush/Change Brake Fluid?
Wondering how often you folks change your brake fluid in your C3's. I got mine together 2 years ago with everything new. It sits in the garage for five or six moths unused. After two years I'm thinking I should do it before putting it up this winter. Too soon?
Last edited by 69L46vert; Nov 8, 2019 at 08:43 AM. Reason: spelted rong
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
Like most folk, about as often as changing auto trans fluid ... when there's other work done on system ... seldom if ever.
You can do better ... don't do as I do.
You can do better ... don't do as I do.
Last edited by jackson; Nov 8, 2019 at 08:43 AM.
Le Mans Master
Joined: Oct 2007
Posts: 7,456
Likes: 977
From: RI, Now Franklin/Nashville TN
You should always change brake fluid periodically on all cars but newer cars can go much longer...10+ years.
On your C3, you should change brake fluid every 4-5 years, at most, to avoid MC issues and more importantly, to help prevent caliper seal leaks.
How do I know?
Well, I have lip seal (NOT O-ring seals) SS VBP calipers that I put on my car in 1985 on a car that sits 99.9% of the time and is not driven in the winter for 4-5 months. I have never had a caliper leak. All I do is change the brake fluid every 4-5 years..that is it. MC is also OEM and factory original......Go figure..........
Rule of thumb Guys: Any fluid needs to be changed at some point...best example is power steering on newer cars with R&P Steering....I have 2 cars with over 200,000 miles on the racks..no leaks..I change the PS fluid every year..I know folks that replace racks constantly because they don't change the fluid...X2 for tranny fluid..even on new cars
On your C3, you should change brake fluid every 4-5 years, at most, to avoid MC issues and more importantly, to help prevent caliper seal leaks.
How do I know?
Well, I have lip seal (NOT O-ring seals) SS VBP calipers that I put on my car in 1985 on a car that sits 99.9% of the time and is not driven in the winter for 4-5 months. I have never had a caliper leak. All I do is change the brake fluid every 4-5 years..that is it. MC is also OEM and factory original......Go figure..........
Rule of thumb Guys: Any fluid needs to be changed at some point...best example is power steering on newer cars with R&P Steering....I have 2 cars with over 200,000 miles on the racks..no leaks..I change the PS fluid every year..I know folks that replace racks constantly because they don't change the fluid...X2 for tranny fluid..even on new cars
Last edited by jb78L-82; Nov 8, 2019 at 09:28 AM.
Burning Brakes
Joined: Dec 2005
Posts: 1,164
Likes: 224
From: Pawleys Island, SC
Anytime I break into the system for any other reason, which seems to end up being every 2 or 3 years or so. If I could get maybe 4 years between brake service/repair of any kind I wouldn't have a problem with waiting that long though.
Le Mans Master
Joined: Oct 2007
Posts: 7,456
Likes: 977
From: RI, Now Franklin/Nashville TN
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,028
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Racer
Joined: Jul 2015
Posts: 396
Likes: 101
From: Lehigh Valley Pennsylvania
I (partially) change my daily drivers' fluid every time I change lining. I push the fluid out the bleeder when I drive the pistons back. I use a turkey baster to suck the fluid out of the reservoir. You don't have to bleed anything using this approach. Gets most of the fluid out, takes 2 minutes and costs me $2. I used this approach on my pickup since new. It is 30 yrs old and has 343,000 miles. Never had a hydraulic issue.
On the cars I don't drive regularly, I just watch the color and suck out the fluid when it gets dark.
On the cars I don't drive regularly, I just watch the color and suck out the fluid when it gets dark.
Thread Starter
Pro
Joined: Jul 2006
Posts: 505
Likes: 25
From: Buxton Maine
You should always change brake fluid periodically on all cars but newer cars can go much longer...10+ years.
On your C3, you should change brake fluid every 4-5 years, at most, to avoid MC issues and more importantly, to help prevent caliper seal leaks.
How do I know?
Well, I have lip seal (NOT O-ring seals) SS VBP calipers that I put on my car in 1985 on a car that sits 99.9% of the time and is not driven in the winter for 4-5 months. I have never had a caliper leak. All I do is change the brake fluid every 4-5 years..that is it. MC is also OEM and factory original......Go figure..........
Rule of thumb Guys: Any fluid needs to be changed at some point...best example is power steering on newer cars with R&P Steering....I have 2 cars with over 200,000 miles on the racks..no leaks..I change the PS fluid every year..I know folks that replace racks constantly because they don't change the fluid...X2 for tranny fluid..even on new cars
On your C3, you should change brake fluid every 4-5 years, at most, to avoid MC issues and more importantly, to help prevent caliper seal leaks.
How do I know?
Well, I have lip seal (NOT O-ring seals) SS VBP calipers that I put on my car in 1985 on a car that sits 99.9% of the time and is not driven in the winter for 4-5 months. I have never had a caliper leak. All I do is change the brake fluid every 4-5 years..that is it. MC is also OEM and factory original......Go figure..........
Rule of thumb Guys: Any fluid needs to be changed at some point...best example is power steering on newer cars with R&P Steering....I have 2 cars with over 200,000 miles on the racks..no leaks..I change the PS fluid every year..I know folks that replace racks constantly because they don't change the fluid...X2 for tranny fluid..even on new cars
Last edited by 69L46vert; Nov 9, 2019 at 07:42 AM. Reason: spelted rong
Le Mans Master
Joined: Oct 2007
Posts: 7,456
Likes: 977
From: RI, Now Franklin/Nashville TN
This sounds like good practical experience to me. And one would imagine that storage conditions may play a part in brake fluid longevity. I don't heat the garage where I store my car. It can get to -25F here in winter and like others, I've had some problems with some of my older cars over time with the fluid absorbing water and corroding and destroying parts like calipers and wheel cylinders. This of course is what I want to avoid. I just flushed my 10 year old Tacoma when rebuilding the calipers and the fluid didn't look all that great with some minor discoloring. The Tacoma fluid had been changed just two years ago when Toyota replaced the frame along with all the brake lines. And these C3's do seem to have more than their share of brake problems which almost always trace back to contamination in the fluid.
I am a little surprised by the some responses that state you don't need to change brake fluid ever...REALLY?
My last thought on this issue is that ANY FLUID in an automobile will NOT last forever...period...and not changing certain fluids will have negative consequences somewhere along the operational continuum of that vehicle.
Brake fluid that is Silicone based (DOT5) does not absorb water which is the achilles heel of regular Dot 3/4 brake fluid. In other words, regular Dot 3/4 brake fluid immediately begins to deteriorate the minute the container is opened and exposed to air. This deterioration cycle continues until the brake fluid is changed the next time. These are facts, not opinion.
If folks never believe in changing brake fluid, go at it, but please do not imply to the uninformed that such action is mostly harmless to the brake system....NOT TRUE....
Not only can potentially deteriorated brake fluid cause harm to the brake system components like the hoses, calipers, seals, master cylinder etc but there is a definite performance loss in the brake system operation as the fluid deteriorates with dirt and water overtime including brake pedal feel, brake pressure application, brake fate resistance when hot, and the risk of complete brake failure.
Last edited by jb78L-82; Nov 9, 2019 at 09:16 AM.
Thread Starter
Pro
Joined: Jul 2006
Posts: 505
Likes: 25
From: Buxton Maine
Well said^^^^^!!!
I am a little surprised by the some responses that state you don't need to change brake fluid ever...REALLY?
My last thought on this issue is that ANY FLUID in an automobile will NOT last forever...period...and not changing certain fluids will have negative consequences somewhere along the operational continuum of that vehicle.
Brake fluid that is Silicone based (DOT5) does not absorb water which is the achilles heel of regular Dot 3/4 brake fluid. In other words, regular Dot 3/4 brake fluid immediately begins to deteriorate the minute the container is opened and exposed to air. This deterioration cycle continues until the brake fluid is changed the next time.
If folks never believe in changing brake fluid, go at it, but please do not imply to the uninformed that such action is mostly harmless to the brake system....
I am a little surprised by the some responses that state you don't need to change brake fluid ever...REALLY?
My last thought on this issue is that ANY FLUID in an automobile will NOT last forever...period...and not changing certain fluids will have negative consequences somewhere along the operational continuum of that vehicle.
Brake fluid that is Silicone based (DOT5) does not absorb water which is the achilles heel of regular Dot 3/4 brake fluid. In other words, regular Dot 3/4 brake fluid immediately begins to deteriorate the minute the container is opened and exposed to air. This deterioration cycle continues until the brake fluid is changed the next time.
If folks never believe in changing brake fluid, go at it, but please do not imply to the uninformed that such action is mostly harmless to the brake system....
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Oh I have seen the result of neglected brake fluid. My 70 GTO sat undriven for an unknown amount of years before I rebuilt the drivetrain and brakes. The car drove and stopped okay before I tore into it. But when I opened the brake cylinders up (drum brakes all around) they had clumps of corrosion that I had to chisel out before I could hone them. I rebuilt them just for the experience but really should have replaced them. Brake fluid is hydrosopic and absorbs moisture which in turn attacks the steels on the inside.
I think the recommended change interval is like only 2 or 3 years but who the can find that much time? In my personal requirement 5 years would be good enough.
Now you can flush the lines and system with denatured alcohol but that would be overkill for most of us and all I do flush out the discolored fluid with my Motive Power Bleeder until each bleed has clear new fluid coming out. Works great for me.
Good luck.
I think the recommended change interval is like only 2 or 3 years but who the can find that much time? In my personal requirement 5 years would be good enough.
Now you can flush the lines and system with denatured alcohol but that would be overkill for most of us and all I do flush out the discolored fluid with my Motive Power Bleeder until each bleed has clear new fluid coming out. Works great for me.
Good luck.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
I think it’s gonna depend on two things primarily. Humidity in your area and how much heat the fluid has been exposed to, ie heavy brake usage.
more of either of these is going to degrade the fluid.
mositure In the fluid will also rust internal components, particularly the low spots in the system ie wheel cylinders.
when racing motorcycles I changed the fluid often as it burned and turned dark from excessive heat making the brakes softer.
more of either of these is going to degrade the fluid.
mositure In the fluid will also rust internal components, particularly the low spots in the system ie wheel cylinders.
when racing motorcycles I changed the fluid often as it burned and turned dark from excessive heat making the brakes softer.
Pro
Joined: Sep 2018
Posts: 535
Likes: 104
From: Chicago, IL
im a fleet mechanic and maintain 300 plus pieces of small equipment and 45 light/heavy trucks, what i have learned through the years is maintenance is very important and most people only do it when the equipment/vehicle is broke. i recommend a brake fluid flush every 2 years. 
Burning Brakes
Joined: Jul 2018
Posts: 979
Likes: 258
From: Maryland
For the lazy types like me gravity bleeding is so easy that changing the fluid isn't that bad. As long as the bleeders aren't frozen shut by corrosion or gunk of course. On this subject, how many have tried using silicon fluid and was it worth the effort? How different is the braking experience - i.e. does the brake pedal have a noticeable softness to it while braking compared to Dot 3/4?
Instructor
Joined: Apr 2007
Posts: 184
Likes: 17
From: GUTHRIE OKLAHOMA
Oh I have seen the result of neglected brake fluid. My 70 GTO sat undriven for an unknown amount of years before I rebuilt the drivetrain and brakes. The car drove and stopped okay before I tore into it. But when I opened the brake cylinders up (drum brakes all around) they had clumps of corrosion that I had to chisel out before I could hone them. I rebuilt them just for the experience but really should have replaced them. Brake fluid is hydrosopic and absorbs moisture which in turn attacks the steels on the inside.
I think the recommended change interval is like only 2 or 3 years but who the can find that much time? In my personal requirement 5 years would be good enough.
Now you can flush the lines and system with denatured alcohol but that would be overkill for most of us and all I do flush out the discolored fluid with my Motive Power Bleeder until each bleed has clear new fluid coming out. Works great for me.
Good luck.
I think the recommended change interval is like only 2 or 3 years but who the can find that much time? In my personal requirement 5 years would be good enough.
Now you can flush the lines and system with denatured alcohol but that would be overkill for most of us and all I do flush out the discolored fluid with my Motive Power Bleeder until each bleed has clear new fluid coming out. Works great for me.
Good luck.
I traded mine for a ‘66 Nova SS about 40 years ago. Still grieving for both of them. LOL