AbstractThe thickener structure of polyurea grease has a crucial effect on its properties. Therefore, it is very important to study the relationship between a thickener structure and physical and performance properties. In this study, polyurea greases were synthesised, having a different number of urea groups in per polyurea thickener molecule. Properties such as dropping point, penetration, oil separation, shear stability and four‐ball wear and extreme pressure (EP) were evaluated. The result shows that properties of polyurea grease vary with the number of urea group per polyurea molecule. Based on molecular theory, the mechanisms explaining these effects are briefly discussed. Copyright © 2010 John Wiley & Sons, Ltd.