Brake fluid in a c3 corvette
Burning Brakes
Joined: Aug 2005
Posts: 1,164
Likes: 1
From: Europe, France
Unlike the DOT 3, DOT 4 and DOT 5.1 ( racing ) which are all glycol based, DOT 5 is a silicon brake fluid and cannot be mixed with the others.
DOT 5.1 has generally the highest boiling point ( 260 °C up to 330 °C ) and is suitable for all disc and drum brake systems.
To achieve optimum performance, bleed the brake system thoroughly to ensure the removal of all old fluid.
These type fluids are hydroscopic meaning they have an ability to mix with water and still perform adequately. However, water will drastically reduce the boiling point of fluid.
In a passenger car this is not an issue. In a racecar it is a major issue because as the boiling point decreases the performance ability of the fluid also decreases.
DOT 5.1 has generally the highest boiling point ( 260 °C up to 330 °C ) and is suitable for all disc and drum brake systems.
To achieve optimum performance, bleed the brake system thoroughly to ensure the removal of all old fluid.
These type fluids are hydroscopic meaning they have an ability to mix with water and still perform adequately. However, water will drastically reduce the boiling point of fluid.
In a passenger car this is not an issue. In a racecar it is a major issue because as the boiling point decreases the performance ability of the fluid also decreases.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
What fluid was 'recommended' by GM for your car may not be the right question. You need to know what type is presently in the brake system. A previous owner could have changed it over. You want to add/replace with the same type fluid that is in the vehicle, unless you want to purge what is in there now [completely] and convert it to something else.
Remove the cover on the master brake cylinder and see if you can detect by color, feel, and smell what is presently in there. If you have any old receipts that a PO provided to you, look for one that was a brake repair shop. Call them and see if they have any records on work done on the car. You might get lucky.
Remove the cover on the master brake cylinder and see if you can detect by color, feel, and smell what is presently in there. If you have any old receipts that a PO provided to you, look for one that was a brake repair shop. Call them and see if they have any records on work done on the car. You might get lucky.
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
Castrol GT LMA and Valvoline Synthetic are good quality Dot 3-4 fluids which are inespensive, widely available, compatible with conventional fluids, and should suffice for most street use. I have my reasons for NOT recommending silicone brake fluid which, among other ills, doesn't mix. FWIW, I like Motul RBF for hardcore use.
TSW
TSW
Last edited by TheSkunkWorks; Aug 9, 2010 at 02:55 PM.
Racer
Joined: Jun 2006
Posts: 476
Likes: 0
From: Easton PA
in my opinion (maybe not others), flush it with dot 5 and forget about it. wont have to change it for almost ever.also non hydrscopic so wont have to worry about moisture in brake system. set it and forget it.
Burning Brakes
Joined: Oct 2003
Posts: 1,090
Likes: 74
From: New Carlisle IN
Depends on what you do with the car. If the car sits for very long periods, Silicone will best serve your needs. It you drive it regularly, a good DOT3-4 will be your best bet. I use the Valvoline synthetic DOT 3-4 in both my vettes and all my other veheicles.
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Heel & Toe
Joined: Dec 2010
Posts: 21
Likes: 0
Brake fluid is hygroscopic meaning it has the ability to attract and hold water molecules from the surrounding environment. I learned this the hard way as I opened the master cylinder on my newly acquired 69 vert and saw nothing but rust. I have a new master cylinder but I need to find out what condition the brake lines are in and if I need to replace them also. Good luck and let us all know what you decide to go with.
