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Checking up on the dealer brake fluid recommendation

 
Old 06-28-2019, 02:10 PM
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tcinla
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Default Checking up on the dealer brake fluid recommendation

On my last visit, the dealer recommended changing the brake fluid. I declined because A) I'm at 24k miles and the service schedule doesn't indicate it and B) I had new rotors, pads and DOT 4 (Motul RBF 660) put in around 10K miles ago. Since i'm all street driving (daily commute and some weekend fun), when do I need to think about new fluid and should I go back to OEM fluid or stay with the DOT 4)

Last edited by tcinla; 06-28-2019 at 02:12 PM.
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Old 06-28-2019, 02:19 PM
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Originally Posted by tcinla View Post
On my last visit, the dealer recommended changing the brake fluid. I declined because A) I'm at 24k miles and the service schedule doesn't indicate it and B) I had new rotors, pads and DOT 4 (Motul RBF 660) put in around 10K miles ago. Since i'm all street driving (daily commute and some weekend fun), when do I need to think about new fluid and should I go back to OEM fluid or stay with the DOT 4)
I would probably do new fluid in 2 or 3 years. Stay with DOT 4.
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Old 06-28-2019, 02:20 PM
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A trusted source told me that GM specifies DOT3 fluid for the street since DOT4 fluid will hold more moisture. Yes, DOT4 has a higher wet boiling point but it still holds more moisture. That moisture can corrode various parts in the brake system. Given the general lack of brake fluid maintenance by the normal car owner it makes sense they would want to keep the system from having problems as long as possible. As an aside: An interesting thing is Ford DOT3 brake fluid. It is rated at a 500 degree F dry boiling point which is above what some DOT4s achieve.

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Old 06-28-2019, 02:46 PM
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Originally Posted by tcinla View Post
On my last visit, the dealer recommended changing the brake fluid. I declined because A) I'm at 24k miles and the service schedule doesn't indicate it
Amazingly (at least for my 14) the brake fluid replacement per the service schedule is at 150K or 10 years whichever comes first.

I track my car so the DOT4 racing fluid gets bleed out a little (a caliper full?) at a time between several events. Thus after about 1 year I've completely flushed the entire system. I wouldn't let DOT4 fluid go any longer then 2 years. They make moisture testers for brake fluid - might best to just test and when its says the moisture content is too high then replace it.
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Old 06-28-2019, 04:06 PM
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I'd just go back to DOT3 if you are not tracking car because of the moisture issue. Why was DOT4 put in?
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Old 06-28-2019, 09:42 PM
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I put it in not knowing about the moisture issue. Now I know. Thanks!
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Old 06-28-2019, 11:00 PM
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I have searched but can't find any data or articles indicating DOT 4 holds more moisture. Could you share where that data is coming from?

Thanks

Last edited by JJoeG; 06-28-2019 at 11:01 PM.
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Old 06-30-2019, 04:17 PM
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DOT4 absorbs moisture more quickly which is why it needs to be flushed more frequently than DOT3. This is why GM calls for DOT3 on the street but DOT4 on the track.
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Old 07-01-2019, 12:49 AM
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All 2019 Corvettes now come with DOT 4 brake fluid from the factory. Also called out in the owners manual.
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Old 07-01-2019, 12:15 PM
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You donít consider what you are doing changing the fluid do you? The goal is to remove moisture from the fluid when you never do?

Originally Posted by JMII View Post
Amazingly (at least for my 14) the brake fluid replacement per the service schedule is at 150K or 10 years whichever comes first.

I track my car so the DOT4 racing fluid gets bleed out a little (a caliper full?) at a time between several events. Thus after about 1 year I've completely flushed the entire system. I wouldn't let DOT4 fluid go any longer then 2 years. They make moisture testers for brake fluid - might best to just test and when its says the moisture content is too high then replace it.
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Old 07-01-2019, 12:37 PM
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Originally Posted by Detroit_Bill View Post
You donít consider what you are doing changing the fluid do you? The goal is to remove moisture from the fluid when you never do?
I am changing the fluid, just not all at once. This is likely not ideal for a street driven car but a common routine in tracked cars.
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Old 07-01-2019, 02:02 PM
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Default I guess it work for you.

The goal is to remove all moisture from the fluid. As you know (but others may not) under track use under extreme heat the water can turn to steam which is compressible and then you have no brakes, hello WALL.
There is moisture in your fluid. If you take some fluid out and add more there is still moisture in your fluid, a very dangerous situation. Do that for a couple years and your fluid has a lot of moisture in it.

I have a power bleeder (motive $40), I just use it to pressurize the system and keep topping it off but it is pretty easy to do by yourself. I would change the fluid once a year just to be sure, not expensive and not difficult.

Originally Posted by JMII View Post
I am changing the fluid, just not all at once. This is likely not ideal for a street driven car but a common routine in tracked cars.
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Old 07-01-2019, 02:11 PM
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DOT4 is now factory fill on 2019s
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Old 07-01-2019, 02:38 PM
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Originally Posted by Detroit_Bill View Post
I have a power bleeder (motive $40), I just use it to pressurize the system and keep topping it off but it is pretty easy to do by yourself. I would change the fluid once a year just to be sure, not expensive and not difficult.
That is how I am doing it as well - push out old fluid and replace with new stuff. I normally go thru two 500ml bottles, but I am not sure if this represents the entire volume of fluid in the system.
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Old 07-01-2019, 04:30 PM
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Originally Posted by JMII View Post
That is how I am doing it as well - push out old fluid and replace with new stuff. I normally go thru two 500ml bottles, but I am not sure if this represents the entire volume of fluid in the system.
That's what I do too. I push a half bottle per wheel,
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Old 07-01-2019, 06:56 PM
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Default Your changing the fluid

If if you are doing that you are changing the fluid. I thought you were doing one squirt per caliper.

My bad, just trying to help.

Originally Posted by redman76 View Post
That's what I do too. I push a half bottle per wheel,
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Old 07-07-2019, 08:11 PM
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My understanding with regular DOT fluid was it should be changed out every 3 years regardless of how few miles.The reasoning was to drain the moisture in the system to prevent corrosion.This may not be the recommendation for the Corvette but it has been recommended by other cars I've owned. Has this now changed?
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Old 07-08-2019, 01:13 PM
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Originally Posted by wonka12_98 View Post
My understanding with regular DOT fluid was it should be changed out every 3 years regardless of how few miles.The reasoning was to drain the moisture in the system to prevent corrosion.This may not be the recommendation for the Corvette but it has been recommended by other cars I've owned. Has this now changed?
Seems OEMs are all over the place with their recommendations...

https://www.cars.com/articles/how-of...1420680336417/
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Old 07-08-2019, 10:11 PM
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Sort of related but what is shelf life of unopened dot 4? I have a liter that has been in the garage for a year and a half or so, I never broke the seal. Just wondering if I should use this or not.

I understand if it has been opened that you should not use it after a year or two?
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Old 07-10-2019, 08:59 AM
  #20  
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Default DOT 4 is standard on 2019s

Dot 4 is standard on 2019s

Originally Posted by redman76 View Post
I'd just go back to DOT3 if you are not tracking car because of the moisture issue. Why was DOT4 put in?
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