Highly viscous heavy oil and bitumen are becoming more important in the world energy mix as conventional resources decline. Any successful in situ recovery process must mobilize the highly viscous bitumen and move it to a production well. Standard methods use heat provided by steam (SAGD) or solvent (VAPEX), with encouraging combinations of steam and solvent (ES-SAGD) but these routes have inefficiencies. Alternative ways of mobilizing bitumen might involve viscosity reduction management of more fundamental controls on bitumen viscosity including managing internal physicochemical interactions between the interacting functional groups on different crude oil molecular components. Here we examine the impact of low molecular weight multiheteroatom species (LMWMH) as molecular Velcro linking high molecular weight moieties together by multiple interactions. Most species tested showed only a viscosity reducing dilution effect whereas THF/aniline as an additive showed an additional viscosity reducing effect particularly at low volume fraction of the additive. Considering that this additive is soluble in water and therefore easily transportable to the subsurface bitumen makes it a promising candidate for enhanced in situ bitumen viscosity reduction and thus improved in situ bitumen mobility.