The Microlon film forms within 1,000 miles (1,600 km) in automobiles. This time is needed for the Microlon resin to get burnished into the pore structure of the metal and form the protective micro-thin film. At this point, you should check your oil. If the Microlon cleaning complex has removed deposits from your engine, the oil will be dirty and should be changed to prevent stress on your filtering system. Any resin that is unused will come out with the dirty oil. Microlon will not change tolerances or replace metal which had been worn away.