I have to disagree with itwonder - a single analysis does have value. It will let you know if your engine is behaving typically, or if there is some significant wear going on. Even if you only ever do 1 sample, you can go on bitog and find others with similar engines and see what kind of results they get to confirm that all is well with your engine.
Of course, having a history and trending it is better, but you have to do the first test to ever get to that point.
Of course, having a history and trending it is better, but you have to do the first test to ever get to that point.