Linalyl oleate (LO), an interesterification product of linalyl acetate (LA) and methyl oleate catalyzed with sodium methoxide, was studied to determine its effectiveness in retarding oxidative changes in soybean oil heated continuously at 180 5 degrees C for 32 h. The identity of LO was established by GC-MS and NMR. LO was tested at levels of 0.05 and 0.1% and compared with the more commonly used synthetic autoxidation inhibitor* methyl silicone (MS) at levels of 5 and 10 ppm. FA changes and conjugated dienoic acid formation were monitored. First-order kinetic equations were used to model the decreases in linoleate (18:2)/palmitate and linolenate (I 8:3)/palmitate ratios. Plots of the data show an inflection point at similar to 11 h. Oils with either level of MS and LO had lower reaction rate constants before the inflection points, and lower conjugated diene values and higher 18:2 and 18:3 percentages at the end of the 32-h heating period than did oil without additives and with LA. LO could replace methyl silicone in soybean oil during deep-fat frying but at levels about 100 times greater. [*We propose to use the term "autoxidation inhibitor" for substances that inhibit autoxidation when added to fats and oils at low concentrations and whose mechanism of action may be unknown. Some may wish to call such substances "antioxidants" but others wish to reserve this term for substances that end free radical chains by hydrogen radical donation. Some refer to methyl silicone as a "polymerization inhibitor," but this term suggests more about its mechanism of action than seems warranted.].