If you have an oil consumption problem ,this may tell you why. If it is due to stuck rings and excessive blow-by. It can also tell you of premature bearing wear. I have said it before, this is a way to help prevent engine failure by knowing what is going on internally. It is cheaper to rebuild the engine then to replace the whole thing do to a spun bearing. I am not saying do it at every oil change, but if you think you have a problem why not. shawn