Its overdue for a flush. 2 year span is correct. I would also verify the front rotors are not too thin. Usually after the third to forth pad replacement the rotors are worn too thin. Thin rotors wont dissapate heat well and could contribute to fade. Also, desending a hill you should manually shift to 2nd. Less strain on your brakes.

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81 300CD (sold) 1972 280 SEL 4.5 (sold) 1966 250 S 4 spd (sold) 1974 450 SL (sold) 86 BMW 325ES (sold), 1973 280C (sold) 1988 300 SE.