text: In addition to monitoring oil contamination and wear metals, modern usage of OA includes the analysis of the additives in oils to determine if an extended drain interval may be used. Maintenance costs can be reduced using OA to determine the remaining useful life of additives in the oil. By comparing the OA results of new and used oil, a tribologist can determine when an oil must be replaced. Careful analysis might even allow the oil to be "sweetened" to its original additive levels by either adding fresh oil or replenishing additives that were depleted.
  Oil analysis professionals and analysts can get certified in compliance with ISO standards by passing exams administered by the International Council for Machinery Lubrication (ICML).
  For purposes of Oil Analysis Program (OAP) trend analysis, replacement, replenishment or drain and flush of lubricating fluids in excess of half an engine’s oil capacity (2.5 gallons or more) will be considered an Oil Change and the engine will be placed in code Charlie (C) for three flights to establish a new working trend. Oil-Wetted Maintenance (OWM) is any replacement of engine components within an oil-lubricated system (bearings, gearbox, pumps, etc.). OWM actions shall be documented on DD Form 2026 and submitted to OAP lab for update of Oil Analysis database.
  (a)	Special Samples can be requested by the laboratory whenever they feel its necessary.
  (b)	Whenever directed by the unit maintenance activity to investigate suspected deficiencies.
  The NDI/JOAP laboratory will set the standards and intervals of oil analysis.
  A typical predictive maintenance technique is ferrography, which analyses iron in oil.