I know this is old but thought it deserved a response. The last two comments confuse me a little because if you are showing high iron in your oil analysis something is coming apart. Was the oil filter element inspected for iron deposits both visually and with a magnet? A lot of times oil analysis will come back clean because the oil filter is doing it's job. I would inspect the oil filter if you haven't already. If there is iron in the oil there is no doubt iron in the filter. Usually if an aircraft has had higher then normal wear levels or a trace amount of iron is found in the filter I release the aircraft and recommend a follow-up oil change in 25hrs. Some times it's a fluke and the oil and filter are clean the next inspection, other time the situation has worsened. It sounds like this problem has been ongoing for quite some so I would highly suggest a more invasive investigation if you haven't done so already.