A 25-75 blend (v/v) of alkali-refined sunflower oil and diesel fuel, a 25-75 blend (v/v) of high oleic safflower oil and diesel fuel, a non-ionic sunflower oil-aqueous ethanol microemulsion, and a methyl ester of sunflower oil were evaluated as fuels in a direct injected, turbo-charged, intercooled, 4-cylinder Allis-Chalmers diesel engine during 200-hour EMA cycle laboratory screening endurance tests. Engine performance on Phillips 2-D reference fuel served as baseline for the experimental fuels.The experiment was conducted to develop prediction equations to determine the effects of alternate fuels on long-term engine perfomance. Least squares regression procedures were used to analyze long-term effects the test fuels had on engine performance and to simultaneously compare the test fuels. Several variables were used to measure engine performance. These response variables were volumetric fuel flow, energy input, power output, brake specific energy consumption, exhaust temperature and exhaust smoke. The predictor variables were time of the EMA cycle and fuel type.Two multivariate tests were performed in this analysis. The first tested the significance of time on the response variable. The second tested the fuel effect. Both tests were significant.The results of the univariate regressions indicated that time had a significant effect only on exhaust temperature. In all other cases, time was not a factor. However, significant differences in the intercepts of the prediction equations were found between tested fuels.