As the usage of petroleum hydrocarbon products increases, soil contamination with diesel and engine oil is becoming one of the major environmental problems. Investigating the countermeasure to remediate soils polluted with oil, has indicated that bioremediation is an effective and useful technique to speed up the cleanup processes. Human and animal health has been seriously threatened by un-controlled release of petroleum hydrocarbons into the groundwater and soil. The oiled area is covered with "fertilizers" that contains microorganisms, like bacteria, in bioremediation process. These microorganisms speed the natural degradation processes already at work. It is thought that the more microorganisms at work, the faster the oil will be removed. In this study, three microbial isolates capable of using engine oil as carbon source were isolated from contaminated soils.