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Using scaling theories and the findings of experimental studies, the possibility of obtaining a new generation of viscosity depressants for decreasing the limiting low temperature of pumpability of lube oils of different natures was investigated.Ensuring the all-season use of lubricants is a permanent, urgent problem. At high and moderate temperatures, this problem is usually solved by using thickeners that increase the viscosity and viscosity index of lube oils, which allows significantly reducing fuel consumption in engines. However, the lower temperature limit of reliable operation of most land vehicles has been restricted for many years to the range of -35 to -40°C. This is basically due to loss of fluidity of lube oils so that cold starting of internal combustion engines and delivery of oils to the vehicle's lubricating system become practically impossible.A generally recognized solution to this problem consists of using high-index, thickened, semisynthetic and synthetic oils instead of ordinary mineral oils processed from mixtures of distillates and petroleum residues. We investigated the mechanisms of regulation of the low-temperature properties of heavy hydrocarbon systems with carbochain high polymers with no depressant properties in the generally accepted sense. The positive effect of the crystalline phase in atactic polypropylene -a propylene stereoblock copolymer (PSBC) -on the viscosity-temperature properties of thickened oils at low temperatures was demonstrated previously, although the solubility of PSBC in aliphatic hydrocarbons is extremely low. The effects of depression of the viscosity at low temperatures not included in modern theories of polymer solutions were identified. For this reason, a hypothesis was advanced concerning the possibility of using scaling theories for explaining these effects [2]. In contrast to most physical quantities, the viscosity is determined in movement of a material body in a closed space (ring, flat, cylindrical, and other shapes) under the effect of external forces. For inhomogeneous hydrocarbon systems such as lubricants, and especially thickened oils, the pumping conditions are determining.It is not accidental that the inadequate term "limiting low pumpability temperature" is used in world practice instead of the term "solid point" or "loss of mobility" of lube oils.0009-3092/06/4203-0196

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