After using my w211 3 times, since a B service. Which included a brake fluid change. On applying the slightist touch to the brake pedal, I'm getting a very annoying sound. It's not easy to discribe. Other than, a squelchey release of fluid or air. Or something that needs oiling. The sound appears to come from the general area of the brake pedal. & lasts, less than a second & not very loud. This happens evey time the brake pedal is touched. Engine on or off. Braking appears normal. Any ideas. Before I take it back to the garage & they tell me it's some other problem. Not associated with the oil change. Which I feel it is.