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Fullerenes are spheroidal carbon clusters typically produced by arcing graphite rods in an inert gas such as helium. This process generates structures including C60, C70 and trace amounts of larger clusters. At ambient conditions, these clusters dissolve in a clear 100N bright stock at mass fractions up to 700 ppm. These solutions have a magenta color which is typical of solutions involving aromatic solvents like toluene. Solution density decreases with increasing mass fraction suggesting that fullerenes act like voids in the mineral oil. The low shear rate viscosity exhibits an unusually strong dependence on the volume fraction of fullerenes in solution. This dependence implies an effective diameter that is at least 50% greater than the molecular diameter. These solutions also exhibit abrupt shear thinning from their low rate value to the base stock viscosity. All of these results suggest that aromatic hydrocarbons adsorb onto the fullerene surface.