Hino 700 E13C mostly take higher load, so engine must able to work under heavy conditions, including late oil change time & sudden initial acceleration. This reason why E13C have two-stage oil filtering, multiple oil jets & largest oil pan to reducing problems from engine oil life issue. As you can see, oil pre-filter element larger than main filter element. This for easier catching metal powders, also main filter element has larger filtration areas for collecting smaller dust particles. These filter elements must replaced simultaneously for optimum filtration performance