Disclosed herein are dual catalyst compositions containing an unbridged metallocene compound, a bridged metallocene compound, a chemically-treated solid oxide, and an optional co-catalyst. These catalyst compositions can be used for the oligomerization of propylene to produce an oligomer product. For example, a heavy propylene oligomer can be recovered from the oligomer product, and the heavy propylene oligomer can be characterized by a high flash point and viscosity index, and a low pour point.