UTTERLY INSANE ADVISE!!! Petroleum products on the disk or pad friction surface will usually render the pads useless and require replacement and a thorough cleaning of the disk surface. I hope you just misinterpreted what these "mechanics" said.

There is a product usually known as "brake paste", available at most auto parts stores, that you can apply to the pad's steel backing plate where it contacts the piston on the inboard side and the caliper housing on the outboard that may help, but you are better off selecting a pad that has low noise characteristics - like PBR Deluxe.

Duke