Search Results

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.

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.