Dot 4 or Dot 5?

[watpress]

I have an 1983 Argo. The service manual says to use Dot 4 brake fluid. The user manual says to use Dot 5. Have no idea what's in there now.

I assume Dot 5?

[Rusty-Gunn]

I'm no expert but I read here to use DOT 5. Its what I put in our Avenger last year when we owned it. Something about it being better for heat.

[Nubs]

Yep

[msafi65]

I was told years ago when DOT 5 came out that it doesn't mix well with DOT 4. I would suggest using DOT 5 and bleed the system until all you get is fresh fluid. 5 has a much higher boiling point, when the fluid boils the steering goes away.

[wern]

Dot 3&4 are glycol based and absorb water.Dot 5 is silicon based so doesnt absorb moisture.The two do not mix and a full change of fluid is required when going from one to the other.

[Tomo]

hi
The difference between all of dot 3 and 4 is the boiling point
More moisture the lowers the boiling point of the fluid . As brakes run hot during normal operation the fluid can then boil and cause brake failure/fade at the very least .
The other reason u need to change the brake fluid is the absorbed moisture causes corrosion of internal metallic items .

DOT 5.1 is normal brake fluid with a higher boiling point equivilant to silicon
The benefit of using a glycol based fluid is it does not compress as much ,so u will get a better feeling pedal in some situations

DOT 5.0 silicon does not mix with glycol types
If u would like to use it there should be a modern fluid available that can be retro fitted easily

tomo

[North Country Tough]

Take a small amount out and put it in a jar with some water in it shake it up see if it separates,DOT 5 silicon will not mix the other will.

[rodp]

Take a small amount out and put it in a jar with some water in it shake it up see if it separates,DOT 5 silicon will not mix the other will.

Good thinking NCT, the simple ways are always the best .