A surfactant system comprising: a) a primary surfactant composition of the kind such as herein descirbed and b) an adjuvant composition comprising 0.1 to about 20% by weight of the surfactant system of (C2-C4)alkoxylated mono(C2-C3)alkanol isostearamide and an optional different second surfactant, wherein the adjuvant composition is substantially a liquid at room temperature and modifies the rheological properties of the surfactant system.