This was why I just loved AOAP. The Army Oil Analysis Program. It saved so much oil and unnecessary maintenance. In your case, it would not help much, since you have to start with a baseline test, and go from there. The analysis would tell you if there was serious levels of metals in the oil. But not if its a long standing problem, or just started. The lab can tell you from where the metal comes from. Which bearing is bad. If rings are bad. Its a great tool. Most people would say the cost precludes it being used in small gen sets. In sets that run high hours, I beg to disagree.