Three dose–response greenhouse experiments were conducted against wild oat separately and synchronically to compare the influence of nine vegetable oils on the effectiveness of three herbicides including imazamethabenz-methyl at 0, 25, 50, 100, 150, and 200 g a.i. ha−1, sethoxydim at 0, 45, 94, 187, 281, and 375 g a.i. ha−1, and sulfosulfuron at 0, 62, 125, 250, 375, and 500 g a.i. ha−1. When vegetable oils were applied alone, only cottonseed had a phytotoxic effect on wild oat. All vegetable oils improved herbicides’ effectiveness significantly. The vegetable oils decreased the ED50 4.03-, 3.06-, and 1.63-fold with imazamethabenz-methyl, sethoxydim, and sulfosulfuron, respectively, when averaged over the nine vegetable oils. In other words, oil receptivity for sethoxydim was lower than for imazamethabenz-methyl and higher than for sulfosulfuron which strongly represents a positive relationship between the oil receptivity and the herbicides’ log Kow. With a slight difference, the vegetable oils were ranked based on their performance in enhancing the tested herbicides to rapeseed, soybean, cottonseed, bitter almond, olive, canola, sesame, castor, and sweet almond oils which represents a negative correlation between the vegetable oils’ performance with its un-saturates/saturates ratio of fatty acids in a theory.

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