Brake Fluid

Brake Fluid I Use

  • Dot 3

    Votes: 21 28.8%

  • Dot 4

    Votes: 12 16.4%

  • Dot 5

    Votes: 26 35.6%

  • Silicon

    Votes: 12 16.4%

  • Other ?

    Votes: 2 2.7%
  • Total voters
    73
  • Poll closed .
I use both silicone (Dot 5) and Dot 3. Naturally, in different cars. Too lazy to change the Dot 3 car to Dot 5.
 
Lanny said:
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Yes, But I meant dot 5.1 and 3 & 4 are all glycol based and
NOT silicone based as dot 5 is..




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Click to expand...

And they can be mixed. I see no advantage to DOT 5 or 5.1 in any car involved in the Ford Barn
 
Many old cars sit for long periods of time, and the dot 3,4 and 5.1 all
attract moisture, and if the car sits for long periods, the moisture
tends to rust the system, especially the wheel cylinders.
The glycol based fluids work OK, if you drive the car monthly
to keep the moisture from settling.

I use dot 5, silicone based fluid, as it Don't attract moisture, and
it don't eat the paint if you happen to spill a drop.




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I put DOT-5 in a '68 Corvette I had and it worked fine for 20 years until I sold the car last fall. However, I have never had so much trouble getting the brakes bled on any other car I owned. I have since gone back to DOT-4. I have an electronic device that will tell you the moisture content of the fluid in your system and whether it is at a marginal level or not. From my experience, the DOT-4 fluid will last at least 10 years (probably more) before it picks up enough moisture to be problematic. At that time, I flush the system and install new fluid. I have "Speed Bleeders" installed in my cars, so that is not a big chore.

Think about this : How many 20 or 30 year old "beaters" on the road are running their original brake fluid installed at the factory? Probably most of them, and I know of no major manufacturer that installs DOT-5. If it were a problem, the legislators and DOT would be all over it, with mandated brake fluid changes, etc.
 
If your going to use Dot 3 you might might well use Dot 4 for the higher boiling point. You can mix them but you might as fell flush the system with new dot 4 fluid.

I would use what your other vehicles use which will probably be dot 4 if they have disc brakes. Your already out of room in your garage.You don't have room two bottles of brake fluid. You could put another 97 carb in that spot!

Dot 4 chart. The dry boiling point is new fluid. The wet boiling point is after it has two-years worth of absorbing moisture. This is why you change it every two-year's. Do this flush, especially on your new vehicles with antilock brake controls. You do not want moisture screwing that stuff up. It gets real expensive. Your hydraulics should last forever if you flush the fluid every two-year's.
 

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I found that dot 4 is better than dot 3. This was a durability test on clutch slave cylinders on a rig. The cylinders were failing, a switch to dot 4 made them pass the test ok.

I've used dot 4 on everything ever since. I have dabbled with silicone, but the last car I have that was silicone is now on dot 4 after a brake overhaul a couple of years ago.

Mart.
 
Dot3 is all I have here and use it in every brake system. I don't need even more confusion of keeping 2 types of brake fluid. Bad enough with two types anti freeze and several grades of motor oil.
 
The Reason new vehicles don't use Dot 5, is because Dot 5 does not
work with the Anti Lock Brake System. The super fast pumping action
of the ABS causes tiny air bubbles in the fluid.





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DOT 5 is Silicon based, and CANNOT be mixed with other fluids. It also does not absorb water, so it can be a good choice for something that sits in storage for long periods of time.

DOT 3 is basic brake fluid.
DOT 4 is the synthetic version of DOT 3, and can be mixed with it.

I don't know enough about DOT 5.1 to give rock solid advice.

I ran DOT 5 in my mustang for a few decades. Never had a problem.
 
I had to replace the master cylinder in my 1947 coupe as it rusted out at the bottom with Dot 3 brake fluid 40 years ago, so I replaced the master cylinder and have been using a silicon based dot 5 brake fluid ever since no problems, the only thing when the coupe is in storage I push the brake pedal down hard every now and again.
 
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