Scientists warn against the dangers of frying food in oil as it release toxic chemicals linked to cancer and heart disease. The negative effects of synthetic antioxidants lead to searching for a substitute with natural recourses. In the present study, fruits of three date palm cultivars; 'Hayani', 'Sewi' and 'Sakouti', were collected at mature stage and date seeds were used for oil extraction. Chemical properties of the oil as well as rancimate measurements were measured to determine the oxidative stability of the oil. Different levels (5, 10. 15 %) of date seed oil were added to crude soybean oil and the oxidative stability for the mixer were then compared to the commercial soybean oil with BHT additive. Pit powder oil content ranged from 8.2-10.6.'Sewi' had the highest total phenols content of phenolic compounds that 183.92 mg among cultivars, while carotenoids content were varied (33.5- 88.5 mg/kg).The fatty acid compositions of all the cultivars were very similar. Rancimat measurements for all cultivars' oil were higher than that of crude soybean oil. Date seed oil addition at different level to soybean crude oil increased the rancimat induction time. Treatment of 'Sewi' oil at 15 % was the best treatment among cultivars and was higher than that of the synthetic BHT effect. The results suggested that the seeds from the examined date cultivars as by product are good source of oil with high quality that may efficiency used as a natural additive to promote the oxidative stability of other vegetable oil.