The authors have been engaged in the verification and basic study of a technology for perfect cleanliness and semi-permanent use of lubricating oil (LO) without any waste oil. Nephrons of animals keep their blood clean. Therefore the technology is called Nephron system because it always keeps LO clean. Nephron system has been in practical use in many marine and cogeneration diesel engines as well as in some other fields for a long time. In the course of their study, the authors have found that also another technology for semi-permanent use of LO has been developed and in practical use. The two technologies differ in their principles of removing LO sludge. Nephron system removes sludge mechanically while another does it electrically. Also, it is reported that a lot of waste LO is generated every day in industrialized countries. On the other hand, there seems to be no basic principle reported, so far, for the permanently perfect cleanliness of LO. Therefore, the authors have studied a basic principle to perfectly remove LO sludge and keep it clean permanently. This paper reports the principle and proposes worldwide R&D and practical use of those technologies of no waste oil for saving natural resources and protecting our environment.