Abstract: A rheological control agent comprises a particulate blend of hydrogenated castor oil and an oligomeric polyamide derived from hydroxystearic acid, one or more saturated aliphatic .alpha. - omega diprimary diamines containing 2, 4, 6, 8 or 10 carbon atoms and one or more saturated aliphatic .alpha.-omega dicarboxylic acids containing from 2 to 10 carbon atoms and/or hydrogenated dimer acids. The oligomeric amide is suitably derived from the reaction of the hydroxystearic acid, dicarboxylic acid and diamine in such proportions that for each mole of hydroxystearic acid there is present 0.05 - 0.5 moles of dicarboxylic acid and a quantity of diamine sufficient to provide from 0.8 to 1.15 amine groups for each carboxyl group in the acid mixture.