Abstract: This research was carried out to investigate the effects of different ratios of waste lubricant sludge to fumed silica and mixing time on characteristics of high temperature grease produced from waste lubricant sludge and silicone oil. The ratios used were 100:0, 90:10, 80:20, 70:30, 60:40, 50:50 and 40:60. In terms of mixing time, it was varied at 1, 2, 3, 4 and 5 h. In this experiment, the grease was prepared by using heating and mixing technique. The grease produced was analysed according to the American Society for Testing and Materials (ASTM) and National Lubricating Grease Institute (NLGI) standard via penetration test, dropping point test, copper corrosion test, Fourier Transform Infra Red (FTIR) and Atomic Absorption Spectroscopy (AAS). FTIR analysis was carried out to study the functional groups present in the grease. AAS analysis was also carried out to determine the concentration of a specific metal element in the grease. The results show that the grease produced with a minimum ratio of fumed silica to sludge (10:90) was high temperature grease with a dropping point of 272.5°C. Further analysis show that the grease produced is high temperature grease with a worked penetration of 270-290 which makes the grease fall into NLGI number of two. It also has a low tendency to corrode copper and very little metal element was present in the grease. It can be concluded that the ratio of fumed silica to sludge and the mixing time of the grease produced significant effect on worked penetration and dropping point of the grease.