Soot dispersibility is an important performance index of diesel engine oil. The dispersion performance of biofuel soot (BS) and 0# diesel soot (DS) in liquid paraffin (LP) and the influence of polyisobutylene succinimide dispersant (T154) were investigated by means of viscosity

spot experiment and particle size distribution. The dispersion mechanisms of BS and DS were investigated by means of X-ray photoelectron spectroscopy and Fourier infrared spectrometer. The surface of BS and DS contained some O-containing functional groups and the oxygen content of BS was higher than that of DS. The effect of oil thickening by DS was greater than that by BS. T154 has a good effect on dispersing BS and DS in LP. The influence of T154 on the BS and LP dispersing system was better than the DS and LP dispersing system. T154 could also be used as a dispersant to disperse BS into lubricating oil. Because of BS surface with O-containing acid groups

such as carboxyl group

and phenolic hydroxyl

it could adsorb T154 by the acid-base reaction with succinimide of dispersant. At the same time

because of BS surface with polar groups

it could adsorb T154 through forming hydrogen bonds with the giving electrons unit of N-H.