WHY IS OIL CHANGE NECESSARY INSPITE OF USING MECHANICAL FILTERS?
Both filters (see comparison) and centrifuges (see table) have a limitation that they cannot adequately remove smaller particles. Yet , it is contaminants below 5 microns, known as “Silt” which are most harmful to the system. Smaller particles alone can enter the clearances in mating parts (typical clearances)and have the capacity to increase erosive wear and also catalyse oxidation. Silt particles exist in much larger numbers(see graph) and over time, as these particles remain in the oil they contribute significantly to build up of sludge and resinous matter and act as catalysts to increase the acid number of the oil (see table above).
