An isothermal thermogravimetric analysis (TGA) method was used to generate a model capable of predicting the results of the Thin Film Micro-Oxidation (TFMO) test in a soybean oil system. Utilizing a series of pseudorate constants and "activation energies", weight loss data from the TGA method can predict oxidation, polymerization, evaporation, and the formation of high molecular weight deposits, normally observed in the TFMO test. These parameters can be used in simple computer simulations which can calculate the weight of each component of a lubricant as it decomposes. This allows evaluation of lubricants without the difficult to obtain TFMO equipment, instead utilizing equipment available in most laboratories.