Which Brake Fluid DOT 3 or DOT 4 ?

I would guess that your Fairmont is running Dot 3 fluid at present - if you flush the system (get rid of all the old brake fuid), you can run either. Dot 3 is cheaper, but moisture drops its boiling temperature more -see above post about loosing brakes, Dot 4 is still pretty cheap (~$10 for a liter of high quality stuff).

Andrew

Denny B wrote:

use DOT3 DOT4 is about 40% more hygroscopic than DOT3. Chip

which dot 3 and which dot 4 ? Castrol LMA both in dot 3 and dot 4 absorbs moisture at a slower rate than Ford heasy duty dot 3, ATE absorbs moisture slower than dot 3 fluids (except for the castrol), motul racing 6000 gets past 2% moisture in a month or two (dot 4, gets wet fast), wilwood fluids abosrb in between the ate and motul.

Depends on which fluid you are talking about.

Andrew

Chip Ste>

I believe it should tell you what to use on the cap of your master cylinder.

Fwed

dot3 is the correct fluid for a fairmont. I personally replace my entire brake system and use dot5 silicone. chip

DOT 3 and DOT 4 are the same stuff, but DOT 4 had higher boiling point etc. - don't worry about it and just use the DOT 4. The two may be mixed without any ill effects.

good luck

nate