Abstract: Flow of a stream comprised of hydrocarbons is improved by introducing into the stream a stable, non-agglomerating suspension comprising:(a) water,(b) highly dispersed in the water, and substantially insoluble therein, and extremely finely-divided, non-crystalline, ultra-high molecular weight, hydrocarbon-soluble, undegraded polyalkene having 2 to about 30 carbon atoms per alkene precursor and an inherent viscosity of at least 20 dL/g, and(c) a small but effective amount of a surfactant having a HLB of at least about 9. The finely divided polyalkene is prepared by polymerization and then cryogrinding below the glass transition temperature of the polyalkene.