Contaminants can enter your gearbox oil by way of vents or the fill tube all through checking/filling. More often than not, nevertheless, contaminants are the results of normal use. The gearbox filter protects versus these contaminants which aids improve gearbox lifestyle. Which is why companies arrived up with inside filters. https://johnnyqzejo.blogars.com/32985472/filter-gearbox-can-be-fun-for-anyone