Brake Fluid

[Blade]

I am putting new brake calipers on the front of my 280SL and would like some advice on brake fluid. Would you continue to use DOT 3 and flush the system or change to a 4 or 5 grade. I don't anticipate using the car for anything but pleasure driving.

Jim

[jameshoward]

Jim,

If you have the time, it's worth doing a search on the site. There's a lot of info and discussion on brake fluids, DOT 3, 4, 5 etc. I'd suggest a bit of background reading might help inform your decision in addition to what is posted here.

I use DOT 3 and change every 2 years. Works fine for me.

JH

[IXLR8]

I have used silicon brake fluid in my 1981 380SL for about 25 years with absolutely no problem. The car is driven only occasionally (32,000 miles), and I have never changed the fluid. When I re-do the brakes on my 230SL, it will be silicon.

Silicon brake fluid is particularly advantageous for cars that are driven only occasionally as the silicon does not adsorb water and rust out cylinders. Cars driven regularly can use DOT 3 or DOT 4 as the regular usage heats the brake fluid and boils off the water.

More modern cars cannot use the silicon brake fluid as it is somewhat more easily compressed than DOT 3 or Dot 4, and this compress-ability affects the functioning of ABS braking systems.

[Blade]

Thanks for the info. I have read many postings on the advantages and disadvantages of syntehic brake fluid, just trying to make a final decision.

Jim

[JimVillers]

Jim .... Read the label on the silicon can, it is not compatible with mineral fluids.  It is an excellent brake fluid but you need to rebuild and flush your system before converting.  DOT 3 & 4 are compatible and DOT 4 is for disk brakes and has a higher dry boiling point.  Dot 4 is better and racing ATE Blue fluid is even better. 

Take the advice and flush your fluid every year or so.  I use ATE Blue and then flush with ATE Gold, when the color changes, it has been flushed.  My next flush, I go back to Blue.