Foam and pleated filters use different types of filter media, with each having its own characteristics.
Foam filters are washable and reusable and can hold a relatively large amount of dirt without significantly affecting airflow. This makes them particularly well suited to road cars and applications where longer service intervals are useful.
Pleated filters use a synthetic filter material designed to provide excellent airflow. As dirt and debris build up, however, airflow can gradually become restricted, so regular cleaning is important.
Neither type normally requires oiling for everyday road use.