Anything wrong with DOT4?
Thread Starter
Racer
Joined: Apr 2018
Posts: 329
Likes: 101
From: Chiggerbranch, MS
Anything wrong with DOT4?
I know the owners manual for my 2014 Stingray says DOT3, but is there anything wrong with flushing and using DOT4? The difference is the boiling point and generally I believe 4 is better than 3. Not talking about DOT 5 or anything like silicone brake fluid. I can't find any previous threads on this which seems odd. Maybe my searcher is busted.
Last edited by wlittle49; Jul 17, 2019 at 11:39 AM.
Drifting
Joined: Jan 2019
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From: Raleigh, NC
DOT 4 contains borate esters that DOT 3 does not. They are compatible unless your system info says not to use it. DOT 5 also has this additive but its not the reason DOT 3/4 are not compatible with DOT 5
Safety Car
Joined: Jul 2018
Posts: 4,303
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From: Margate, FL
DOT4 is recommended for track use where higher boiling points are required.
However DOT4 attracts water faster thus requiring more frequent flushes.
I don't see any real benefit of running DOT4 on a street driven car.
However DOT4 attracts water faster thus requiring more frequent flushes.
I don't see any real benefit of running DOT4 on a street driven car.
Race Director
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From: Out Where the Buses Don't Run, Eglin AFB/ Niceville FL
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The 2019 GS and Z06 went to DOT4 from the factory (Stingray may have as well, not sure) so I don't see it being an issue.
Safety Car
Joined: Jul 2018
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From: Margate, FL
I checked the 2019 manual and they recommend changing the brake fluid (DOT4) every 3 years now. Contrast this with my 2014 where GM lists brake fluid service at 10 years (DOT3). Honestly 10 is way too long, its more like 3 years for DOT3 and 1 year for DOT4 based on my research.
Drifting
Joined: Dec 2015
Posts: 1,410
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From: Germantown Maryland
So what exactly is the stuff I see at the auto parts stores labeled Dot 3/4? Is it really DOT 4 and just their way of labeling to show it is compatible with 3?
Like this: https://shop.advanceautoparts.com/p/...1458/7080002-P
Edit: I just read the web page I linked and it indeed as I speculated. The fine print says it is "high quality DOT4 fluid that is compatible with DOT3".
Like this: https://shop.advanceautoparts.com/p/...1458/7080002-P
Edit: I just read the web page I linked and it indeed as I speculated. The fine print says it is "high quality DOT4 fluid that is compatible with DOT3".
Last edited by raylo; Jul 17, 2019 at 06:57 PM.
Melting Slicks
Joined: Sep 2005
Posts: 2,568
Likes: 264
From: Near Charlotte NC
If i'm not mistaken,some years the Brake fluid was DOT3 and the Clutch fluid was DOT4.Probably given the spec by two diff engineering depts.
As far as I know,it's fine to run DOT4 in both.I think Pentosin makes ( or did make) the fluid for GM.
Correct me if I'm wrong.
\db2
As far as I know,it's fine to run DOT4 in both.I think Pentosin makes ( or did make) the fluid for GM.
Correct me if I'm wrong.
\db2
Thread Starter
Racer
Joined: Apr 2018
Posts: 329
Likes: 101
From: Chiggerbranch, MS
Humm. Somebody is incorrect. Either the post here that say DOT4 absorbs water faster than DOT3 or this from a respected vehicle maintenance website:
"The basic difference between DOT3 and DOT4 is the boiling point. This is the temperature under which the fluid evaporates and also how prone to absorbing water it is. Both DOT3 and DOT4 are hygroscopic, meaning they absorb water.
Due to its lower boiling point, DOT3 is more prone to water absorption. Consequently, DOT3 boils under hard braking much easier, which makes it less suitable for activities requiring aggressive braking."
https://www.thevehiclelab.com/dot3-vs-dot4-brake-fluid/
Which it be? IDK
"The basic difference between DOT3 and DOT4 is the boiling point. This is the temperature under which the fluid evaporates and also how prone to absorbing water it is. Both DOT3 and DOT4 are hygroscopic, meaning they absorb water.
Due to its lower boiling point, DOT3 is more prone to water absorption. Consequently, DOT3 boils under hard braking much easier, which makes it less suitable for activities requiring aggressive braking."
https://www.thevehiclelab.com/dot3-vs-dot4-brake-fluid/
Which it be? IDK
Last edited by wlittle49; Jul 17, 2019 at 07:24 PM.
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Racer
Joined: Apr 2018
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From: So Cal
So who you going to believe: a reputable vehicle website, or a random poster? I say Dot 4 is a better option. It's what GM is now using on C7 brake systems. Of course if you use dot 3 you will be fine too. Either will serve your purpose. But go with Dot 4
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Humm. Somebody is incorrect. Either the post here that say DOT4 absorbs water faster than DOT3 or this from a respected vehicle maintenance website:
"The basic difference between DOT3 and DOT4 is the boiling point. This is the temperature under which the fluid evaporates and also how prone to absorbing water it is. Both DOT3 and DOT4 are hygroscopic, meaning they absorb water.
Due to its lower boiling point, DOT3 is more prone to water absorption. Consequently, DOT3 boils under hard braking much easier, which makes it less suitable for activities requiring aggressive braking."
https://www.thevehiclelab.com/dot3-vs-dot4-brake-fluid/
Which it be? IDK
"The basic difference between DOT3 and DOT4 is the boiling point. This is the temperature under which the fluid evaporates and also how prone to absorbing water it is. Both DOT3 and DOT4 are hygroscopic, meaning they absorb water.
Due to its lower boiling point, DOT3 is more prone to water absorption. Consequently, DOT3 boils under hard braking much easier, which makes it less suitable for activities requiring aggressive braking."
https://www.thevehiclelab.com/dot3-vs-dot4-brake-fluid/
Which it be? IDK
I can't prove anything, but I've seen several comments from brake companies and racers that the DOT4 absorbs moisture more rapidly than DOT3. Your quote is the only one I've seen that claims the opposite.
If DOT4 absorbed moisture more slowly than DOT3, there would be no reason for DOT3 to be used.
Personally, I use DOT4 and flush it annually.
Burning Brakes
Joined: Jan 2016
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DOT 4 is Factory fill on 2019s
Safety Car
Joined: Jul 2018
Posts: 4,303
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From: Margate, FL
Correct. And per my 2014 manual the DOT4 clutch fluid is recommended to be replaced every 2 years. Now for the 2019 both the clutch and brake fluid (both DOT4) should be replaced every 3 years. So it seems even GM can't figure out how quickly these fluids absorb water. To be safe I wouldn't let either of them regardless of type to sit in a car for anymore then 3 years.
Drifting
Joined: Dec 2015
Posts: 1,410
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From: Germantown Maryland
Unfortunately Chevy made the clutch slave cylinder bleeder bleedin' inaccessible. So short of the ranger method you are talking some $$ to get this done. Be nice if some vendor designed a replacement bleeder that could be reached or some other clever way to make this easier. Maybe attach a line to the OEM bleeder and connect to an accessible remote mounted bleeder and leave the OEM open.
Correct. And per my 2014 manual the DOT4 clutch fluid is recommended to be replaced every 2 years. Now for the 2019 both the clutch and brake fluid (both DOT4) should be replaced every 3 years. So it seems even GM can't figure out how quickly these fluids absorb water. To be safe I wouldn't let either of them regardless of type to sit in a car for anymore then 3 years.
Last edited by raylo; Jul 18, 2019 at 10:17 AM.