It is generally assumed that some qualitative factors, including high organic fraction, size, density, and surface chemistry of the core etc., will dominate the liquid-like behavior of the hybrid nanofluids. For quasi one-dimensional PEG-functionalized carbon nanotubes (PEG-CNTs), this paradigm may be quite different. Our investigations show that controlling the functional density, CNT contents, and aspect ratio of the nanopipes will extremely change the rheological properties of the nanofluids. Namely, a highly viscous longer PEG-MCNT system exhibits a liquid-like behavior throughout all the temperature range of 20-80 degrees C, but a low viscous shorter PEG-MCNT behaves as an elastic solid and even can give a solid-liquid transition at 56.7 degrees C. As we model the response of the nanofluids with a deformation mechanism governed by viscous interaction, we have 1/Jx = K x exp(-E-a/dRT) (or a/x = K x exp(-E-a/RT)). Then we gain a quantitative understanding of the relationship between functional density, CNT volume fraction, aspect ratio, and viscoelastic response of the quasi I D nanofluids. Once the oxidation of MCNTs ran be controlled, the unexplored solid-like behavior of the nanofluids becomes possible. It is notable that the control for specific rheological nanofluids will be achieved through simply controlling the oxidation time of nanotubes, and controlled viscoelastic nanofluids may find important applications in nanoscience.