Contaminants can enter your gearbox oil by vents or maybe the fill tube during checking/filling. Usually, nonetheless, contaminants are the result of standard wear. The gearbox filter guards versus these contaminants which assists strengthen gearbox everyday living. Which is why manufacturers arrived up with inner filters. These filters are available https://finnbggec.bligblogging.com/34718253/getting-my-filter-gearbox-to-work