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The trouble-free operation of an engine during and after starting at low temperatures is achieved by an uninterrupted supply of oil to points of friction, i.e., by the oil's pumpability. A key parameter in pumpability is wax, and in particular its composition, concentration and morphology. Wax or paraffin compositions of engine oils are dependent upon the basestocks used in the formulation. The hydrocarbon compositions of lube basestocks and the carbon number distribution for each hydrocarbon class (n-paraffins,isoparaffins, cycloparaffins, aromatics) depend upon the crude oil's source and more importantly on the manufacturing technology used. In North America, there are essentially four process pathways used to produce lubricant basestocks: solvent extraction or hydrocracking, followed by solvent dewaxing or catalytic dewaxing.

A key element in low temperature engine oil pumpability is wax, and in particular its composition and behavior. The wax composition is determined by the basestocks used in the formulation and its impediment to oil flow is reduced by additives [wax crystal modifiers]. Basestocks are desirable mixtures of hydrocarbons in which the unwanted components are weeded out by refinery separation and conversion sciences. The refinery unit operations take into account the chemical and physical properties of the hydrocarbons that are present in the crude oil. This hydrocarbon molecular selectivity is predicated upon [A] vapor pressure or molecular weight/structure, i.e., vacuum pipestill, [B] chemical bond strengths, i.e., hydrocracking, [C] solubility, i.e., solvent dewaxing/extraction, and [D] molecular shape/chemical bond strengths, i.e., catalytic dewaxing. The refinery unit operations can be combined to manufacture basestocks by four pathways.

A key element in low temperature engine oil pumpability is wax, and in particular its composition and behavior. The wax composition is determined by the basestocks used in the formulation and its impediment to oil flow is reduced by additives [wax crystal modifiers]. Basestocks are desirable mixtures of hydrocarbons in which the undesirable components are weeded out by refinery separation and conversion sciences. The refinery unit operations take into account the chemical and physical properties of the hydrocarbons that are present in the crude oil. This hydrocarbon molecular selectivity is predicated upon [A] vapor pressure or molecular weight/structure, i.e., vacuum pipestill, [B] chemical bond strengths, i.e., hydrocracking, [C] solubility, i.e., solvent dewaxing/extraction, and [D] molecular shape/chemical bond strengths, i.e., catalytic dewaxing. The refinery unit operations can be combined to manufacture basestocks by four pathways.

The wax crystallization process is an important factor in tow temperature engine pumpability, and one key parameter of this process is wax composition. Lube oil wax is a mixture of three paraffin types: each one with its own concentration and carbon number distribution. The latter is dependent upon the boiling point range of the basestock and the wax precipitation temperature as well as the degree of dewaxing. The paraffin types are homologous when one basestock is used to formulate a 10W base oil, but when two basestocks are present, the wax is a dumbbell mixture of these paraffins. These 10W base oils have different rheological properties—yield stress and apparent viscosity. However, in the presence of a flow improver, these base oils have similar rheological behavior.