All very interesting reading. All I can say is having replaced the radiators on my three LS's there was one that clearly was in danger. I'm not sure how flushing the radiator regularly would have helped as the corrosion was starting on the outside and was fairly severe in places, not the radiator itself but the connections on it. My last one was full main dealer serviced and looked OK, although it spent its life garaged. I'm sure we concern ourselves too much with these "what if" issues. I did replace my current one, although having lived its life in Japan probably wasn't needed. It did however mean that like my previous ones I was able to give it new Toyota coolant and replace the transmission rubber hoses, as on a previous one a hose was split and not far off breaking.