Brakes noise
 

300e 2.8 1993 Front brakes just start making some rough noise Similar to the noise when the pads are getting to the metal. But I took the whell off and they are ok, 3/4 of the pad left and the disks look new. They have about 20K( disks and pads) and I do 90% highway driving with verry few stops. Usualy last pair of pads last me around 60K with no problem.
The pads and the disks are original from Germany.
The noise is getting worst between 20mph and zero.
I did clean the brakes with that Spray can Brake cleaner. It was ok for about 2-3 days then it started again!? What could be?
Thanks