Heavy crude oil shows high viscosity combined with low mobility, which affects the efficient transportation through pipelines. Drag has long been identified as the main reason for the loss of energy in pipeline fluid transmission and other similar transportation channels. The main contributor to this drag is the viscosity as well as friction against pipe walls, which will result in more pumping power consumption. Various methods such as heating, upgrading, dilution, core annular flow, and emulsification in water have been used for their transportation. The influence of toluene and naphtha as a viscosity and drag reducing solvent on flow of Iraqi crude oil in pipelines was investigated in the present work. The effect of additive type, concentration, pipe diameter, solution flow rate, and heating on the percentage of drag reduction (%Dr) and percentage flow increase (%FI) were the variables of study. The maximum drag reduction was observed to be 40.48% and 34.32% using heavy oil flowing in pipeline diameter of 0.0508 m I.D. at 27°C containing 10 wt% naphtha and toluene, respectively. Also, the dimensional analysis is used for grouping the significant quantities into dimension less group to reduce the number of variables. Copyright © Taylor & Francis Group, LLC.