In developed countries there are so many discarded plastic disposals from various kinds industry and cities. One of authors company ( Ecology System) has developed a new recycle system and apparatus to liquefy these plastic disposals into fuel oils. These discarded plastic are melted and evaporated first, and their vapors are condensed and extracted after passing through various metal catalyzers for decomposition. The recycled oils are different one by one according to the kind of raw plastic, and generally it has high heating value with rather big density, and their total weight are about 60_80 % of raw plastics. The recycled oils are fed to Diesel engines of several factories as a 30_40% blended fuels with gas oil. Recycle of plastics by this method above will be very good contribution to energy and environments of the earth. In this paper is showed used of the Cracked PE ( Polyethylene) blending oil for engine performance.