Different methods of reducing the viscosity of heavy crude oil to enhance the flow properties were investigated. Experimental measurements were conducted using RheoStress RS100 from Haake. Several factors such as shear rate, temperature and light oil concentration on the viscosity behavior have been studied. This study shows that the blending of the heavy crude oil with a limited amount of lighter crude oil provided better performance than the other alternatives. Experimental measurements in terms of shear stress tau-shear rate gamma, and yield stress tau(0) were conducted on the mixture of heavy crude oil-light crude oil (O-light). The results showed a significant viscosity reduction of 375 mPa s at a room temperature of 25 degrees C. This study shows that the heavy crude oil required a yield stress of 0.7 Pa, whereas no yield stress was reported for the heavy crude oil-light crude oil mixture. (C) 2010 Elsevier Ltd. All rights reserved.