The viscosity of liquid organic systems is increased by adding thereto an organophilic clay gellant which is the reaction product of a smectite clay having a cation exchange capacity of at least 0.75 milliequivalents per gram and from 1.00 to less than 1.20 milliequivalents per gram of clay of a methyl benzyl dialkyl ammonium salt, wherein the two alkyl groups independently contain from 16 to 18 carbon atoms, and from 0% to 1% water in the absence of a polar organic dispersant for the gellant.