Two series of imidazolium-based ionic liquids (ILs) were tested as rheological modifiers heavy crude oils. ILs with the 1-butyl-3-alkylimidazolium cation optimize effect on viscosity at low concentrations, whereas those 1-benzyl-3-alkylimidazolium are similarly effective only higher which is due to a stronger IL–IL interaction respect IL–asphaltene interaction. The most [C6bim][PF6], [phetbim][...