I've got a '96 E320, bought new, now at 52k miles. I've been on a 2 year coolant flush, replacement cycle -- always done by a great Mercedes Benz dealership in Arlington, VA - American Service Center. Recently retired, I moved to Venice, Florida (in Sarasota County - just south of the City of Sarasota) and found that the local dealership suggested I replace "cracked" lower control arm bushings and replace "worn" brake pads and rotors. I carefully inspected these parts and also got a second technical opinion ... There were no cracks in the control arm bushings and the brake pads and rotors are good for another 15,000 miles -- I had just replaced them about 18 months back at around 35,000 miles.

So .... , I found a local mercedes benz (master) technician not associated with the dealership ... I asked him to flush and replace the coolant. He went ahead and replaced the the thermostat and housig o-ring. He showed me the radiator outgoing fluid and it was clear, with no particles in the fluid. He repeated same with the engine block outgoing coolant. He suggested we just do a dump and refill and not flush. We used MB Coolant and distilled water. I was a bit perplexed at not recommending a flush - heck we were there .. why not? ... but I went ahead given his experience and I didn't want to sour the relationship from the start. I know he is a thorough guy and not lazy. Finding a good MB tech who will work for $40 on the side ... is a rare thing.

Should the system have been flushed eventhough the outgoing coolant was clear and there were no signs of visible particles? Why wouldn't you flush the system??

I use Mercedes Benz coolant/anti-corrosive exclusively -- how often should I replae the coolant? Every two years? Three years? More? Thanks.