If you only see it flicker when you step on the brakes, it may be the sensors telling you the fron pads are near end. If it's spongey, that's another matter. Also, the book officially calls for dot4 fluid.
2004 C240 Wagon 203.261 Baby Benz
2008 ML320 CDI Highway Cruiser
2006 Toyota Prius, Saving the Planet @ 48 mpg
2000 F-150, Destroying the Planet @ 20 mpg
And remember folks, Only You Can Prevent Hilliary.