Contaminants can enter your gearbox oil by means of vents or the fill tube throughout examining/filling. Most of the time, however, contaminants are the result of regular wear. The gearbox filter safeguards against these contaminants which will help enhance gearbox everyday living. Aged automatic transmissions usually have steel mesh filters. https://holdenyqdob.thelateblog.com/34593943/the-filter-gearbox-diaries