The use of diesel fuel in diesel engines when they run produces large amounts of environmental emition due to the high flame tem temperature when combustion also high quantities of used lubricating oils produce annually, and the disposal process has caused serious enviro mental problems, so it must purify to use it again The aim of this preparation of emulsifier fuel from waste lubricating oil which have several advantages such as reduce the gases pollutants emulsion and invests the waste lubricating oilThe emulsifier fuel was prep rated from waste lubricating oil after simple physical treatments and surface active agent materials with water that necessary for preparation the emulsion ,the prepared fuel used in internal combustion engine It wase found that ,the optimum condition for preparation are :water percentage 10%,the concentrated of surface active agent 0.2% ,the time of mixing 2min, and the mixing rate 4000 rpm to produce the emulsion that more stable along time . It was found that ,the specific gravity for emulsifier fuel which has water 10% , 20% ( 0.8730, 0.8754) ,the rotational viscosity for the same emulsifier fuel was (23.5, 29.4) cp