Because synthetic lubricants are superior to conventional petroleum lubricants. Petroleum lubes are refined from crude oil, a natural substance pumped from the earth and containing diverse chemicals. Some of the chemicals in petroleum oil are detrimental to the lubrication process and to the lubricated components. For example, some petoleum oil chemicals invite oxidation in high temperature operations.
Oxidation qickly destroys lubricant integrity.
Synthetic lubes, on the other hand, are not refined from crude oil, but constructed from pure chemicals selected for their ability to lubricate. The purity of synthetic lubricant basestocks significantly reduces lubricant oxidation, which promotes the ability of synthetics to be used in higher temperature applications than conventional lubes may be and promotes their ability to be used for extended drain intervals. Synthetics are also free of the paraffins found in conventional petroleum oils. The molecular uniformity of carefully selected synthetic lubes promotes superior lubrication and friction reduction, which in turn promotes superior heat control, wear control and energy efficiency. Molecular uniformity also helps synthetics maintain their protective viscosity in high temperature operations, which also promotes superior wear control.