Contaminants can enter your gearbox oil via vents or perhaps the fill tube through checking/filling. Most of the time, having said that, contaminants are the result of normal use. The gearbox filter guards towards these contaminants which can help enhance gearbox existence. Old automatic transmissions normally have steel mesh filters. https://filter-gearbox65207.blogdeazar.com/34260301/the-ultimate-guide-to-filter-gearbox