DOT-3 or DOT-4 ?
Thread Starter
Racer
Joined: Jan 2005
Posts: 418
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From: Houston Texas
DOT-3 or DOT-4 ?
The standard factory-fill brake fluid, at least in my '16 base Stingray, was DOT-3. What was the factory-fill for the C-7 Z51 ?
Anyone know whether the C-8 will be the same or all C-8's getting DOT-4 ?
Anyone know whether the C-8 will be the same or all C-8's getting DOT-4 ?
Race Director
Joined: Jan 2014
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From: Fulshear, TX
Nearly all vehicles get DOT3 from the factory due to longer life. Prestone DOT4 or ATE TYP 200 are both good upgrades for an aggressively driven performance street car. ATE rates their street life @ 3 years so that's what I run.
Safety Car
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2025 C8 Stingray of the Year Finalist - Unmodified
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Most applications call for a DOT3 (401F dry/284F wet) or DOT4 (446F dry/311F wet) fluid, which is considered a higher performance fluid since it can handle more heat. While both fluids are glycol ether based, DOT4 contains a certain amount of borate ester which allows it to handle more heat.
DOT5 is a silicone-based fluid that was developed for use where moisture or water was almost certain to be a factor in the braking system, such as military applications. While DOT5 has a higher boiling point (500F dry/356F wet) than DOT3 or DOT4, DOT5 exhibits more compressibility than glycol ether brake fluid. There are DOT4 fluids with boiling points that exceed DOT5 so there’s really no need to consider using DOT5 for on-road use.
DOT3 and DOT 4 cannot be mixed with DOT5 fluid. They are incompatible and if mixed, brake failure may occur. Moreover, there are serious compatibility issues when using DOT5 in a system that was engineered to use DOT3 or DOT4. Also, users should take care not to mix DOT3 and DOT4 fluids as there may be brake system compatibility issues. Always consult your owners manual and use the type of fluid specified for your vehicle.
DOT5 is a silicone-based fluid that was developed for use where moisture or water was almost certain to be a factor in the braking system, such as military applications. While DOT5 has a higher boiling point (500F dry/356F wet) than DOT3 or DOT4, DOT5 exhibits more compressibility than glycol ether brake fluid. There are DOT4 fluids with boiling points that exceed DOT5 so there’s really no need to consider using DOT5 for on-road use.
DOT3 and DOT 4 cannot be mixed with DOT5 fluid. They are incompatible and if mixed, brake failure may occur. Moreover, there are serious compatibility issues when using DOT5 in a system that was engineered to use DOT3 or DOT4. Also, users should take care not to mix DOT3 and DOT4 fluids as there may be brake system compatibility issues. Always consult your owners manual and use the type of fluid specified for your vehicle.
Racer
Joined: Jan 2020
Posts: 426
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From: Boston
The best brake fluid IMO is Motul 600. It’s the only fluid I haven’t boiled or had fade on the track. Even if you don’t track the car it’s the only fluid I’ve used that I noticed a pedal difference the moment I got in the car after a flush from another DOT4 fluid.
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Le Mans Master
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Yea GM changed to DOT4 at some point during C7 production due to availability of DOT3. You can top off DOT3 with DOT4, as they are allowed to mix, but if you can get DOT3, get DOT3. I think you can even use DOT 5.1 (which is not like DOT5 its DOT5 spec but chemically identical to DOT 3/4, aka glycol-based)
Team Owner
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St. Jude Donor '13
Yea GM changed to DOT4 at some point during C7 production due to availability of DOT3. You can top off DOT3 with DOT4, as they are allowed to mix, but if you can get DOT3, get DOT3. I think you can even use DOT 5.1 (which is not like DOT5 its DOT5 spec but chemically identical to DOT 3/4, aka glycol-based)
The C7 2017 Manual says to use DOT3 and change every 5 years, 2019 says to use DOT4 and change every 3 years.
I tried to find the moisture absorption rates and boiling points over time of some DOT3 and DOT4 fluids, but all I get are dry and wet boiling points with no indication of how long it takes to get "wet". Do you have any info?
I use DOT4 and flush every Spring so not a big deal for me, but others are less frequent.
Le Mans Master
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AFAIK, most DOT4 starts off with higher boiling points than DOT3. DOT4 absorbs moisture more rapidly than 3 and eventually may degrade to where it has a lower boiling point, but that takes a while.
The C7 2017 Manual says to use DOT3 and change every 5 years, 2019 says to use DOT4 and change every 3 years.
I tried to find the moisture absorption rates and boiling points over time of some DOT3 and DOT4 fluids, but all I get are dry and wet boiling points with no indication of how long it takes to get "wet". Do you have any info?
I use DOT4 and flush every Spring so not a big deal for me, but others are less frequent.
The C7 2017 Manual says to use DOT3 and change every 5 years, 2019 says to use DOT4 and change every 3 years.
I tried to find the moisture absorption rates and boiling points over time of some DOT3 and DOT4 fluids, but all I get are dry and wet boiling points with no indication of how long it takes to get "wet". Do you have any info?
I use DOT4 and flush every Spring so not a big deal for me, but others are less frequent.
