what type of brake fluid should I use in my 66 mustang? this will be the first time that any fluid has been in this system.

 

I've heard that synthetic brake fluid can cause issues with seals in your system and that the only real world advantage is that it withstands 20% more heat so it is not as prone to cause fade during very aggressive driving. So it seems unless you are using the car for racing it is probably best to stick with the DOT fluid for durability and reliability.

 

DOT 3 for topping off or replacing the stock fluid.

http://jimsgarage.wordpress.com/2007...t-4-and-dot-5/

http://www.xs11.com/xs11-info/tech-t...ntroversy.html

edit>>>> Being somewhat ignorant of the differences between DOT 3 and DOT 4, I read the above links in order to actually KNOW what I already supposed....

You can top off or flush with either DOT 3 or DOT 4, (providing DOT 5 has not been used) if flushing I don't see a good reason not to go with DOT 4.

 

DoT3 or DoT4 will work fine. Use whichever is cheaper.

If you're going to be road racing, then step up to a racing type fluid; I use Wilwood 600.

DO NOT use DoT5. It's a synthetic, expensive, doesn't mix with the glycol based fluids, Hydrophobic, and has no real advantage.

 

I used dot 3 on mine because its cheaper then dot 4 and I'm not going to be racing so i don't need the higher boiling point in dot 4