A non-aqueous wellbore servicing fluid comprising a rheology modifier wherein the rheology modifier comprises a reaction product of a polysulfide, a dimer acid and a polyfunctional amine. A method of conducting an oilfield operation comprising placing an oil-based mud comprising a rheology modifier into a wellbore wherein the rheology modifier comprises a reaction product of a polysulfide, a dimer acid and a polyfunctional amine.